Help! Can not reinstall the U3 edition!

When I started my Avast! (U3 Edition) one day, it can’t update its virus database, so I quit the program and remove my Sandisk U3.

I restarted the U3 and started the Avast, it said lack of a “language.dll” file (or sth. like that, I can’t remember its name clearly) and I had to reinstall it. So I did. But during the installing, it said install failed and I had to quit.

I’ve tried both the Sandisk version and the general version. But neither of them can be properly installed.
I’m planning to buy it after the trial date, but now, I cannot even install it.

Need to reinstall avast home edition 4 in order to remove permanently from my computer.Thank-you

likeren, on what are you trying to install it?
This is the forum for avast home/pro.