Error message on trying to run Avast

Left my pc whilst Avast was running a scan. When I came back the “Virus found” pop-up was displayed, so clicked on the “move to chest” button (recommended action). The pop up box went but I then noticed that the pc clock had stopped about 45 minutes earlier, and I couldn’t click on any of the task bar buttons etc. PC wouldn’t reboot, had to switch off and on again. I now cannot run Avast as I get the following message:

An attempt was made to load a program with an incorrect format
program cannot set properly into main storage.

There is also a link to the FAQ’s, but that tells you not to do if on Avast 4.7 (but doesn’t give you an idea of what to do!!)

The Error Log reports: Storage query "INSERT INTO LocalProperties (Object, Property,Val) … failed. Error description: "database disk image is malfor…

I have tried rebooting and system restore without success. I also tried deleting the avast4.db file, (suggestion on this forum regarding a similar problem) but cannot as “file being used”. (I have tried turning off the On-Access protection but still cannot delete the file). The on-access scanner seems to be running OK.

Another post suggests selecting the Repair option in Add/Remove programs … should I try that?

Yet another post suggests uninstalling and re-installing. If I do this, do I have to re-register or can I use the same Licence Key? I’ve been using Avast for so many years I cannot remember anything about the registration process.

Can anyone please give me some help on what to do please?

It won’t be bad.

Yes.

Go to the SSL page version and register from there: https://secure.avast.com/scripts/register.php?lang=ENG

See the tutorial: http://www.avast.com/files/tutorials/insert_key.htm