I'm not an idiot, I know how to clear market cache. That isn't what I'm talking about.
In RC33 you could only clear browser cache, which would do nothing for market cache. Now w/ cupcake, you can clear market cache from settings--> manage apps. This is all well and good, but it doesnt solve the problem.
Do a little experiment. Look at your available phone memory and write down the amount of free mb's.Take your G1 and go onto the market and look at applications non-stop for 1 hour. After doing so, write down the amount of free mb's. Now, go into manage apps and clear your market cache. It doesn't clear the memory you used browsing the market.
because you need to reboot to reclaim and if thats not doing the trick for you then i would call tmobile and replace the device i have never had this issue