Yup, just had this problem at a client on their Exchange server. Took half an hour for the login process, then many things were slooooooooooooooow.
I identified the problem from an internet search and disabled the APC service and everything worked fine on reboot. So I set about deinstalling the APC software.
During the deinstall it TWICE shut off power to the servers, BANG! (this was a BIG unit with three small servers on it), then turned it right back on.
The sudden shutdowns damaged the Oracle database for their main MRP/Accounting software requiring thousands of dollars expense and downtime to put them back in business.
Fortunately their in-house support guy was watching over my sholder when the UPS shut off power so I didn't get blamed for doing something wrong.
Anyway, I have even less warm fuzzys about APC than I did before.