Help with chip thermal issue needed

I have an old M-Audio NRV10, using a Firewire interface. It's in a cold environment and refuses to connect with the PC immediately when powered on. I replaced a couple bulging caps on the power supply and near the PLCC "chip field" on the PCB close to the Firewire connector, to no avail. In leaving the bottom plate off, I discovered if I warm that general area with my heat gun, it responds by connecting right away - and stays connected indefinitely after the heat is removed.

Obviously I'd like to put the mixer back together again, as it is now an open chassis set upon a piece of plywood. Handy to point the nozzle in there to deliberately warm those components, but hardly in a shape I would want to leave permanently.

Anything I can do? Or is it just the nature of these, certain, high speed digital chips to not work when it's cold. There's a couple 3 terminal parts close by and I read 3.3V, when a connection was active. Unsure if those could be suspect as root cause. Thanks for considering my problem!
 
I had a faulty TL431 reference in an SMPS - highly temperature-dependent. When the SMPS warmed up, the reference => output voltage dropped to less than a half, causing the powered device to fail. Maybe your issue is similar - a temperature-dependent power supply, causing undervoltage when cold.