What application?
Remove/reinstall app, make sure mb/chipset drivers and gpu drivers are up to date....
If WIndows itself will not launch, delete partition, recreate, quick reformat, and start over.....
Ensure your mb's BIOS is correctly configured (single/double/triple channel) for your DDR3 modules, correct voltage, correct quad freq 266/333, etc), latency settings as per your mem manufacturer.
Drop to a single stick of mem in a required slot if necessary.