Windows 7 Professional 64-bit

blue screen error 0x0000001A or other ccodes or  IRQL_NOT_LESS_EQUAL

My laptop DELL M4500

coming with windows 7 professional 32-bit, 8GB RAM (3.52GB usable)

because 32-bit recognizes up to 4GB RAM only,

I clean installed the 64-bit version...

after installation I got blue screen error after 5-10 minutes of operation.

I removed one of  two 4GB RAM sticks, no more blue screen error.

I assumed the one stick I had removed earlier was a defective one... and it seems this sort of error happens to Windows 7 64-bit only.