I've copied below part of my post from the Upgrading area, because it seems to be relevant to this topic:
I upgraded to the latest software version 39-14 on receiving my tablet from eBay last week, and have been unable to install most new applications since - particularly galling since I bought the tablet to make use of mediastreamer. I get "Unable to Download. Package not found" from Application Manager - even with the latest refresh. If I download the packages from Maemo.org and then try to install from file, the main package fails because clinkc-av isn't available, but clinkc-av gives "Incompatible package" - very frustrating.
Can anyone help? These problems with packages, libraries etc. give a very poor impression of Linux as a platform to us newbies, which is a pity because the Tablet itself seems to be a brilliant piece of kit.