What problem can be found while deploying ASP.NET application in both 32 bit and 64 bit OS?

Actually i used int16 for conversion in ASP.NET application. it is working fine in 32bit OS like Windows 2003. but when i deployed my application in windows 2008 64bit OS then system crashed at the conversion point.

so what can i do at this situation and what will be other problems (if any) for 64bit OS

Thanks 

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Masud