Hard reset / reinstall programmes?

I had to hard reset my acer n30 the other day.

Now when I try to reinstall any of the programmes it tells me that they are already installed. However, I can't run any of them without reinstalling.

Is there a simple solution or do I have to reinstall each one?

My one current thought is that you sometimes have to also uninstall them from your actual computer. If your on XP, go to start, setting, control panel, then Add or Remove programs. Then uninstall all programs there were on your PDA

Good luck