sometimes sql is returning wrong data to application

this problem is strange and i am not able to find out what happens

i am using freetds + iodbc + qt and i am connection to mssql 2005 database

*sometimes* i get wrong result from long varchar field. usually its good when
query is launched at the beginning and it suddnly stop working when it happens
later, when application is running for several minutes.

when i compiled libtdsodbc.c without optimalizations (-O0 instead of -O2 in
Makefile in odbc directory) then everything started to behave well and this
didn't happened anymore

it looks to me that something wasn't initialized properly with optimalizations
enabled, but i am not able to find out what exactly it could be. when library
was compiled with -O2 there were some warnings, maybe they were related, maybe
not, i don't know.

i tried to do some tracing, but with -O0 there is no problem and with -O2
tracing is not very useful so i learned nothing.... i hope developers will have
more luck