Hi There,
There might be hope for your phone. That has happened to me yesterday as well, I couldn't access anything, that message for force quit kept coming up once a second!(I couldn't even click on anything). I wrote to the HTC customer service, they replied today. See what they suggested:
I understand how frustrating it can be to receive a force close message on your T-Mobile My Touch 3G Slide. Please go on your device to Home, Menu, Settings, Applications, Manage Applications, and locate the process that is providing the force close message. Please clear the data for the application once you have located the process. Perform a soft reset on your device by removing your battery, wait five seconds, and reinsert your battery. Perform a hard reset if a soft reset does not work on your device. This operation will delete all data on your device back to factory settings. Please make sure you have synchronized your HTC Device with HTC Sync on your computer or Gmail on your device. With the phone turned off, press and hold the VOLUME DOWN button, and then briefly press the POWER button. Wait for the screen with the 3 Android images to appear, and then release the VOLUME DOWN button. Press VOLUME DOWN to select CLEAR STORAGE, and then press POWER. When asked to confirm, press VOLUME UP. Please test the concern on your HTC Device after you have performed a hard reset.
If this doesn't work, I would take the phone back into the TMobile store and see if they can replace it for you. I was lucky I had my phone for 3 weeks and it was still in a 30 day warranty (they can replace your phone for 30 days after u buy it if there's anything wrong with it); or, if you have a phone protection plan they should be able to help you as well. Either way, if none of the above works I'd stop by at a TMobile store and see what they can do for you.
Hope things work out for you!