wierd bug, help :(

[seprez]

hi, i got my evo a few days ago and about 2 days ago it started crashing

for example, the first time it happened i went into the market place and the phone crashed where i couldnt do anything on the screen and none of the bottom buttons worked

i did the soft turn off and it came back up to the screen lock

at that point the buttons work and the phone vibrates but i cannot slide the screen lock down to open the phone no matter how hard i try.

i took out the battery and it worked, but this error keeps occuring every day about 20 times, i dont want to have to keep taking the battery out everytime

i called bestbuy to exchange it but if you guys know a fix i would love to hear it