Notes/Domino 6 and 7 Forum : Domino 6.5 server crashing every couple minutes

I am desperate for help! Can anyone help? I have recently upgraded a Domino server from 6.0.3 to 6.5, and it's been crashing ever since. Here's the fatal thread:

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### FATAL THREAD 64/67 [ nSERVER:07bc: 1768]
### FP=0x0731fb6c, PC=0x60194a3e, SP=0x0731fb60, stksize=12
### EAX=0x4ae410ce, EBX=0x00000310, ECX=0x00004356, EDX=0x00000000
### ESI=0x00000001, EDI=0x078e10b0, CS=0x0000001b, SS=0x00000023
### DS=0x00000023, ES=0x00000023, FS=0x00000038, GS=0x00000000 Flags=0x00010293
Exception code: c0000005 (ACCESS_VIOLATION)
############################################################
@[ 1] 0x60194a3e nnotes._GetCounterOffset+30 (78e10b0,310,3ef82cc,28)
@[ 2] 0x601945d0 nnotes._Win32ProcessStats@4+320 (3ef82cc,3ef82cc,ffb9b0,0)
@[ 3] 0x601940d8 nnotes._PSGetDominoProcessInfo@4+1000 (3ef82cc,3ef8824,2ad31e8,3ef8c34)
@[ 4] 0x1005ccb5 nserverl._UpdatePerfList@4+501 (f01040ae,731fea8,1005b324,2ad31f0)
@[ 5] 0x1005c22e nserverl._LISTSRCUpdate@4+14 (2ad31f0,3ef82cc,731fec0,1005b2db)
@[ 6] 0x1005b324 nserverl.__PSUpdatePSHeadL@4+36 (3ef82cc,3ef0000,3ef82cc,3ef8c34)
@[ 7] 0x1005b2db nserverl._PSUpdatePSHead@4+43 (3ef82cc,59780001,3ef82cc,1)
@[ 8] 0x10057cda nserverl.__PSUpdatePerfStats@4+58 (3ef82cc,59780001,231838c,6d22003c)
@[ 9] 0x10057c1a nserverl._PSMain@4+90 (3ef82cc,0,3e8,fe6ebc)
@[10] 0x1005aeb6 nserverl._PlatformStatsTask@8+582 (6d22003c,5c740001,3,848)
@[11] 0x100016cb nserverl._Scheduler@4+763 (0,848,0,0)
@[12] 0x60114924 nnotes._ThreadWrapper@4+212 (0,0,848,0)
[13] 0x7c4e987c KERNEL32.SetThreadExecutionState+551

############################################################
### PASS 2 : FATAL THREAD with STACK FRAMES 64/67 [ nSERVER:07bc: 1768]
### FP=0731fb6c, PC=60194a3e, SP=0731fb60, stksize=12
Exception code: c0000005 (ACCESS_VIOLATION)
############################################################
# ---------- Top of the Stack ----------
# 0731fb60 00000000 00000004 000000e6 0731fd4c |............L.1.|

@[ 1] 0x60194a3e nnotes._GetCounterOffset+30 (78e10b0,310,3ef82cc,28)