By application errors do you mean the little dialog in Windows that states something like 'The memory at 0x3057400 could not be "read".'? If so it's almost certainly a software problem; it doesn't mean that the memory is faulty, it's more likely that the application tried to read a memory segment it didn't have access to or deallocated somewhere, or something similar. If your PC goes down with a STOP error and a blue screen, it's very likely a hardware or driver problem. A physical memory read error in my experience causes the whole kernel to die.
First off check for viruses and malware. You could then try to turn off your ring 0 services like anti-virus and anti-spyware software which might be interfering with normal application. If that doesn't solve things, I'd just format and reinstall everything. Hope that helps
