Root phone turns off when in market

Hi guys, i've tried searching this but no luck.

I rooted and romed my g1 yesterday, all seemed to go successful running CyanogenMod 5.0.8-DS.

Its seems all great, running smoothly, everything working well, battery doesnt drain. Until I went into the market, I had not far off a full battery and the phone died on me.

Now i know theres meant to be a recalibration period by draining the battery then charging it to full, so I did this. But ive just gone on the market again and its just turned the phone off again. Turning it back on shows a really low battery when i originally had a decent life.

edit: its just happened while i was sorting my email, its as if the battery icon isnt working :S