Here's the Crash Report. I was playing on a server.

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 21/07/13 2.51
Description: Rendering screen

java.lang.IndexOutOfBoundsException: Index: 4, Size: 4
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at axt.a(SourceFile:102)
at awv.a(SourceFile:80)
at axt.a(SourceFile:116)
at bfb.b(SourceFile:718)
at ats.S(SourceFile:686)
at ats.d(SourceFile:619)
at net.minecraft.client.main.Main.main(SourceFile:101)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at axt.a(SourceFile:102)
at awv.a(SourceFile:80)
at axt.a(SourceFile:116)

– Screen render details –
Details:
Screen name: axt
Mouse location: Scaled: (280, 73). Absolute: (561, 333)
Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2

– Affected level –
Details:
Level name: MpServer
All players: 3 total; [bdf['NiubbaXD'/24785, l='MpServer', x=-855,30, y=68,62, z=-1560,53], bev['aVoman98'/3726, l='MpServer', x=-867,44, y=67,00, z=-1580,84], bev['courtstar4'/5369, l='MpServer', x=-858,50, y=67,00, z=-1571,50]]
Chunk stats: MultiplayerChunkCache: 121
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (-927,67,-1600), Chunk: (at 1,4,0 in -58,-100; contains blocks -928,0,-1600 to -913,255,-1585), Region: (-2,-4; contains chunks -64,-128 to -33,-97, blocks -1024,0,-2048 to -513,255,-1537)
Level time: 349722379 game time, 389342166 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: adventure (ID 2). Hardcore: false. Cheats: false
Forced entities: 67 total; [oc['entity.ItemFrame.name'/11, l='MpServer', x=-873,06, y=69,50, z=-1568,50], oc['entity.ItemFrame.name'/12, l='MpServer', x=-872,50, y=69,50, z=-1569,06], oc['entity.ItemFrame.name'/13, l='MpServer', x=-871,94, y=69,50, z=-1568,50], oc['entity.ItemFrame.name'/14, l='MpServer', x=-876,50, y=69,50, z=-1565,06], bev['courtstar4'/5369, l='MpServer', x=-922,38, y=67,00, z=-1578,72], oc['entity.ItemFrame.name'/15, l='MpServer', x=-877,06, y=69,50, z=-1564,50], ua['§cVillager§6 - Lvl 5'/6314, l='MpServer', x=-856,50, y=67,00, z=-1584,03], oc['entity.ItemFrame.name'/17, l='MpServer', x=-855,06, y=70,50, z=-1555,50], bev['alphaboys'/1199, l='MpServer', x=-900,59, y=67,50, z=-1577,50], oc['entity.ItemFrame.name'/16, l='MpServer', x=-876,50, y=69,50, z=-1563,94], bdf['NiubbaXD'/24785, l='MpServer', x=-855,30, y=68,62, z=-1560,53], oc['entity.ItemFrame.name'/19, l='MpServer', x=-835,06, y=69,50, z=-1582,50], bev['courtstar4'/5369, l='MpServer', x=-858,50, y=67,00, z=-1571,50], oc['entity.ItemFrame.name'/18, l='MpServer', x=-863,50, y=70,50, z=-1547,06], ok['Painting'/9, l='MpServer', x=-938,94, y=74,00, z=-1567,00], oc['entity.ItemFrame.name'/21, l='MpServer', x=-835,06, y=69,50, z=-1582,50], oc['entity.ItemFrame.name'/20, l='MpServer', x=-835,06, y=69,50, z=-1582,50], oc['entity.ItemFrame.name'/23, l='MpServer', x=-834,50, y=69,50, z=-1581,94], oc['entity.ItemFrame.name'/22, l='MpServer', x=-834,50, y=69,50, z=-1581,94], oc['entity.ItemFrame.name'/24, l='MpServer', x=-833,94, y=69,50, z=-1582,50], bev['alphaboys'/1199, l='MpServer', x=-882,84, y=67,00, z=-1609,75], bev['jcmri'/6052, l='MpServer', x=-881,03, y=68,00, z=-1511,94], bev['courtstar4'/5369, l='MpServer', x=-858,50, y=67,00, z=-1571,50], bev['Fartaugh'/1716, l='MpServer', x=-837,09, y=69,00, z=-1589,53], bev['HBK8877'/3721, l='MpServer', x=-844,25, y=67,00, z=-1573,19], ua['§cVillager§6 - Lvl 5'/6297, l='MpServer', x=-822,50, y=67,00, z=-1597,66], ua['§cVillager§6 - Lvl 5'/6296, l='MpServer', x=-886,66, y=67,00, z=-1568,63], ua['§cVillager§6 - Lvl 5'/6298, l='MpServer', x=-849,28, y=76,00, z=-1584,28], ua['§cVillager§6 - Lvl 5'/6301, l='MpServer', x=-843,00, y=67,00, z=-1552,56], ua['§cVillager§6 - Lvl 5'/6300, l='MpServer', x=-854,53, y=67,00, z=-1570,66], bev['Fartaugh'/1716, l='MpServer', x=-734,01, y=67,00, z=-1565,14], ok['Painting'/9, l='MpServer', x=-938,94, y=74,00, z=-1567,00], sc['§cGuard Golem§6 - Lvl 25'/6286, l='MpServer', x=-839,47, y=67,00, z=-1571,00], bev['Snowstorm29'/3830, l='MpServer', x=-783,44, y=60,00, z=-1575,69], bev['Snowstorm29'/3830, l='MpServer', x=-882,00, y=65,97, z=-1575,00], bev['Fartaugh'/1716, l='MpServer', x=-926,50, y=67,00, z=-1599,50], bev['ARM_PIT_JIUCE'/3018, l='MpServer', x=-745,06, y=68,16, z=-1576,94], bev['xbboyxero'/1299, l='MpServer', x=445,66, y=75,00, z=-1620,72], bev['xbboyxero'/1299, l='MpServer', x=445,66, y=75,00, z=-1620,72], ua['§cVillager§6 - Lvl 5'/6242, l='MpServer', x=-834,50, y=67,00, z=-1562,08], ua['§cVillager§6 - Lvl 5'/6241, l='MpServer', x=-830,88, y=67,00, z=-1562,97], bev['Snowstorm29'/3830, l='MpServer', x=-781,59, y=60,25, z=-1576,13], bev['Fartaugh'/1716, l='MpServer', x=-725,75, y=67,00, z=-1557,24], bev['ARM_PIT_JIUCE'/3018, l='MpServer', x=-794,47, y=67,52, z=-1581,69], bev['ARM_PIT_JIUCE'/3018, l='MpServer', x=-722,55, y=67,00, z=-1519,32], sc['§cGuard Golem§6 - Lvl 25'/6606, l='MpServer', x=-889,22, y=67,00, z=-1574,22], ua['§cVillager§6 - Lvl 5'/5402, l='MpServer', x=-890,06, y=67,00, z=-1563,41], ua['§cVillager§6 - Lvl 5'/5403, l='MpServer', x=-882,09, y=67,00, z=-1564,84], ua['§cVillager§6 - Lvl 5'/5406, l='MpServer', x=-881,84, y=67,00, z=-1572,00], ua['§cVillager§6 - Lvl 5'/5404, l='MpServer', x=-868,41, y=67,00, z=-1571,84], ua['§cVillager§6 - Lvl 5'/5405, l='MpServer', x=-887,61, y=67,00, z=-1573,89], bev['alphaboys'/1199, l='MpServer', x=-927,00, y=67,00, z=-1600,00], bev['HBK8877'/3721, l='MpServer', x=-882,00, y=67,00, z=-1529,56], bev['aVoman98'/3726, l='MpServer', x=-867,44, y=67,00, z=-1580,84], bev['kelvinkasher'/950, l='MpServer', x=670,22, y=139,00, z=-2182,38], bev['kelvinkasher'/950, l='MpServer', x=670,22, y=139,00, z=-2182,38], bev['Fartaugh'/1716, l='MpServer', x=-837,09, y=69,00, z=-1589,53], ua['§dArmour Merchant'/119, l='MpServer', x=-868,53, y=68,00, z=-1546,44], bev['Apple21301'/975, l='MpServer', x=-950,50, y=40,50, z=-1553,50], ua['§dArmour Merchant'/118, l='MpServer', x=-854,16, y=68,00, z=-1560,56], ua['§dWeapon Merchant'/116, l='MpServer', x=-836,47, y=67,00, z=-1595,47], bev['alphaboys'/1199, l='MpServer', x=-926,50, y=67,00, z=-1599,50], bev['Eater_of_Cake'/640, l='MpServer', x=387,53, y=69,00, z=-1579,41], bev['Eater_of_Cake'/640, l='MpServer', x=387,53, y=69,00, z=-1579,41], ua['§cVillager§6 - Lvl 5'/5925, l='MpServer', x=-849,56, y=67,00, z=-1541,88], bev['kelvinkasher'/950, l='MpServer', x=-950,50, y=39,67, z=-1553,50], bev['aVoman98'/3726, l='MpServer', x=-867,44, y=67,00, z=-1580,84]]
Retry entities: 0 total; []
Server brand: craftbukkit
Server type: Non-integrated multiplayer server
Stacktrace:
at bda.a(SourceFile:284)
at ats.b(SourceFile:1761)
at ats.d(SourceFile:628)
at net.minecraft.client.main.Main.main(SourceFile:101)

– System Details –
Details:
Minecraft Version: 1.6.2
Operating System: Windows XP (x86) version 5.1
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 26782400 bytes (25 MB) / 122912768 bytes (117 MB) up to 1037959168 bytes (989 MB)
JVM Flags: 1 total; -Xmx1G
AABB Pool Size: 7343 (411208 bytes; 0 MB) allocated, 1223 (68488 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.6.2
LWJGL: 2.9.0
OpenGL: RADEON XPRESS 200 Series SW TCL x86/SSE2 GL version 1.4.5648 WinXP Release, ATI Technologies Inc.
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Pack: Default
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 1568 (87808 bytes; 0 MB) allocated, 258 (14448 bytes; 0 MB) used