I noticed this problem last night. I go to install an app (I've tried this with a few different apps), and it will download just fine, but installation is unsuccessful. I am able to update the apps that I already have on my phone, I just can't get any new ones. I've tried clearing my market app cache, and I've also tried installing them with my SD card unmounted. Does anyone have a solution, or a phone number I can call? I have a Motorola Cliq through T-Mobile, and everything is up to date on it.