Market Error 101
Explanation: Some users have gotten this error while downloading new apps from the Andoid Market and having the download fail.
Tricky Error, try the following but there are reports the problem is with Google and they are working on a fix on their backend..
Go to Menu, then 'Settings'.
Scroll down to 'Applications'
Usually the third option is 'Manage Applications' pick it.
After you have selected Manage Applications, it could take 30-90 seconds to load depending on the number of apps on your Android device.
In this list, look for 'Market', this is the Android Marketplace App.. click on it.
Click on 'Clear Cache' Just like Internet Explorer (and Netscape, Opera, Firefox, etc..) you need to clear the 'crap' out of the cache at times.. This is no exception.. Not completely sure what piece of code/data is getting stuck in the cache and casuing problems.
Now you can go back to the Applications menu and clear the cache for other Android core apps such as 'Browser', 'Google Apps' and 'Checkin Service'.
I'd shutdown and restart the phone and you should be fine onec you've cleared the cache of these apps. You can also go and clear the cache of other apps such as your instant messaging, email, etc... Same process. I'd like to eventually see a 'clear all apps cache' button..
If this still fails, sign out of your sync'd google account, and sign back into your google account (restart phone), and that has appeared to get around the bug.
On a side note, in each application, you can clear the cache and in many case you can 'Uninstall Updates'.. so in the future, if you install an update and an App stops working, this is where you go to roll back the update to the previous working version.