OK, closer inspection has only revealed the following - whether it's the problem or not I don't know. I can't see it causing an intermittent problem (in that it stopped working, worked for 5 minutes, then died completely on me from then on) but there is a 3-pin SMD component near the AC power plug with what looks like a section of casing missing.

Pictures (Sorry for poor quality):

Overall view:


Component view:


Could this have anything to do with it?