It may be powered related. It's a long shot, but not outside the realm of possible weird errors. Trust me, I've seen some odd stuff in my ~20 years of dealing with video conversion and editing work.
Are you using a surge protector?
While better than nothing (i.e., direct into a wall outlet) -- it's still mostly a nothing.
Consider a UPS with AVR
UPS = uninterruptable power supply
AVR = automatic voltage regulation (a.k.a.
a "power cleaner")
Go for an APC, not a Cyberpower or some no-name. (Although I'd give acknowledgment that the "Geek Squad" brand from Best Buy does seem okay, for the better models.)
A small one runs about $40-60.
has them: http://www.amazon.com/gp/redirect.ht...reative=390957
They're also locally available from OfficeMax, Office Depot, Staples and Best Buy. Also Microcenter, Fry's, CompUSA and TigerDirect if you live in one of the places where they have walk-in stores. Look in the Sunday ads (or the online sites for the store, to see the ads). Sometimes the office stores also mail you coupons, so you can get like $5 off $35 or $10 off $50. (Just watch for the "excludes technology items" BS disclaimers. Those are the worthless coupons. Like we're going to buy $50 in paper, envelopes and paper clips as a normal consumer?)
I run almost everything off a UPS, because it's safer. The units will sacrifice themselves for bad surges, and if power dips or goes out, the battery protects you from hard shutdowns, which are NOT good for electronics or computers.