Well I would check out the battery and charging system first. Some times with Subaru the charging lights will never come on when the car is not charging, I don't know why but it's pretty damn annoying.
Just the other day I went to go shopping in the 93 Imprezza that I've been trying to put together for the past year, I got to a stop light and turned on the turn signal and the radio shut off
I then went through the light and started to get on the highway and hte car would not accelerate, noticed that the tach was not working at that point. I had to pull over to try and figure out what was happening, when I did I shut off the AC and blower fan and the radio and tach started working again
So I left them off and the car would run better, enough to get me the store. When I got to the store I tried to roll the windows up and the they would barly move and the tach died again, at this point I had a pretty good idea of what was going on, and sure enough after I shut the car off it would not restart again
It was not charging at all and the warning lights never came on.
So go get your system checked, I think Autozone does it for free or maybe even a local shop (I know my shop will check it out for you real quik with no charge) to see if you got a problem. You don't want to end up stuck at Stop and Shop with a dead car.