IIRC, Dreamcasts behave erratically if they get dirty inside. Here's what I found searching Google with what I remembered about it:
For some reason Dc's did get some bad press for hardware faults.I have come across a few bad un's,but the most common fault seems to be the console reset fault.This is when the Dc starts to load a game then resets itself.
Personally I used to put it down to being that time of the month,since mine did it for a while the worked perfectly.
After getting half life and the dc being "on one" I decided to browse to see if this was a fixable problem,which it is and it's so simple.But it does mean taking the thing apart.(come on now,NOBODY still has a Dc thats still under warranty)
On the left side,after you take the case off,is the psu board,and near the front you'll see 5 or six prongs sticking up through a connector.Just Ease the board up,After unscrewing the screws of course,and clean the prongs,preferably with a soft cloth and some wd40 or similar.Put it back together and voila,one perfect Dc.(you did remember to put the screws back didn't you)
(From
http://www.roguenoid.co.uk/archives/000094.html )
Dunno about splashing WD40 around in your machine, but this solved crashing and reset problems for most people.
