mlesniak 22 Light Poster

Hi. I have a problem when I try to scan from any of the applications on my computer. When I try to scan it always fails and I may or may not get a message from the host application. In Paint Shop Pro 7 for example I get the message "The server threw an exception". I can click on OK to cancel the message but then I am unable to end the TWAIN session normally, using Paint Shop Pro. If I try to close Paint Shop Pro I get the following message:;
"A TWAIN acquire session is currently running. It must be shut down before exiting. Do you want Paint Shop Pro to close your TWAIN data source for you?". If I click on YES, it does not work and I am still left with a Paint Shop Pro Window titled "[ACQUIRING]".
I have tried uninstalling my scanner software and re-installing to no avail.
If anyone has any suggestions, please let me know.
I am running Windows XP Professional.
I know that there is no problem with the scanner because I can connect to the scanning device by HTTP and scan images perfectly well that way. It's just not as convenient.
The thing is that I don't know when this problem started but I suspect it was when I uninstalled Norton Anti-virus (a version supplied by my ISP).