Driver_irql_not_or_equal stop 0xD1 BSOD

The computer stops sometimes after a few minutes and sometimes after a few hours with a blue screen. On this screen I get the above message with a range of numbers (0xfe93edac, 0x00000002, 0x00000001, 0xef42888f). On searching with google I can't find anything on what is going wrong here or which hardware of driver is being faulty.

 

Does it says anything about any file most probably with 'SYS' extension ?

 

It gives on the second line "SYMTDI.SYS - ADDRESS EF42888F base at EF421000, DateStamp 432effdf "

 

Are you using Norton? if yes, this may probably help http://www.file.net/process/symtdi.sys.html

 

Thanks for the info, it was very helpfull.