Your problem... although it seems to be connected with Kasper is more likely an IRQ conflict.
I don't know how to view all the irq's in Win 7 ... except to look at each device in the device manager .. one at the time... first check the irq for the printer then see if you can find anything else that uses it.
I hate all AV programs that run all the time. They cause so many problems... and where are people finding so many viruses that they need to always be on guard? Scanning for viruse once a week or month is frequent enough... unless your system starts acting funny.