Solved Crash upon joining server

[PureLiqiud]

Hello everyone,
5 minutes ago, me and a friend were playing Mindcrack on my server when suddenly he crashed. Now everytime when he tries to join he crashes, wich isn't happening with other server. I also can't seem to find his player.dat in the server files.

Friend's specs:
Windows 7
Mindcrack version V8.0.1
No mods were added to the modpack.

Server specs:
1024MB ram
E3-1220/E3-1270 V2 Series Quad Core CPU Server is runned on SSD cards and i'm hiring it from Voxel Host.

Crash report:

2013-02-09 14:30:22 [INFO] [STDERR] java.lang.IndexOutOfBoundsException
2013-02-09 14:30:22 [INFO] [STDERR] at com.eloraam.redpower.core.ItemExtended.d(ItemExtended.java:33)
2013-02-09 14:30:22 [INFO] [STDERR] at up.i(Item.java:458)
2013-02-09 14:30:22 [INFO] [STDERR] at up.l(Item.java:598)
2013-02-09 14:30:22 [INFO] [STDERR] at ur.r(SourceFile:334)
2013-02-09 14:30:22 [INFO] [STDERR] at atr.a(GuiIngame.java:406)
2013-02-09 14:30:22 [INFO] [STDERR] at ban.b(EntityRenderer.java:982)
2013-02-09 14:30:22 [INFO] [STDERR] at net.minecraft.client.Minecraft.J(Minecraft.java:882)
2013-02-09 14:30:22 [INFO] [STDERR] at net.minecraft.client.Minecraft.run(Minecraft.java:771)
2013-02-09 14:30:22 [INFO] [STDERR] at java.lang.Thread.run(Unknown Source)

 

[PureLiqiud]

The problem has been solved, but it came with a price. We had to delete Bukkitforge, reset the map, restart the server for the map to render and after that reinstall bukkitforge. Hope this helps others with the same problem.