Erroneous Low Memory Warning

A Lenovo ThinkCentre M90p has started throwing a low memory warning even though the computer has 6GB of memory:

While it's possible, I don't think the problem is malware. Scans with Malwarebytes and Microsoft Security Essentials come up clean. Hitman Pro will not work because the machine used to join a domain. The RAM passed memtest86 tests nine times with no issues. The hard drive passes diagnostics (both Western Digital and SpinRite) with flying colors. There are no bulging capacitors on the motherboard. The system passes Passmark's Performance Test without issue.

I'm out of places to look for solutions. The original complaint is that the computer would operate very slowly. It could take as much as a minute to open IE or Firefox. My thought for tonight is to create a new OS build on a new hard drive and see whether I'm fighting a hardware problem.

via Bleeping Computer Last 20 Posts http://www.bleepingcomputer.com/forums/t/509520/erroneous-low-memory-warning/