invalid page fault in module MSVBVM60.DLL

when i run application.exe built in vb6 sometimes i get following error
"application.exe caused an invalid page fault in
module MSVBVM60.DLL at 0167:73449e79.
Registers:
EAX=00630858 CS=0167 EIP=73449e79 EFLGS=00010246
EBX=00000002 SS=016f ESP=00630000 EBP=00630940
ECX=00000000 DS=016f ESI=0040691c FS=29b7
EDX=006308fc ES=016f EDI=00000000 GS=0000
Bytes at CS:EIP:
e8 db 94 fe ff 57 50 e8 4a 95 fe ff 8b f0 59 3b
Stack dump:
00000020 00630858 00630018 03897d54 00000000 004f1d6c 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 "

but same error is not thrown in debug mode.
can anyone tell me why this exception comes.

Perhaps it is compiled with the Assume no aliasing optimising switch but the code does have aliasing in it?