Canon Multipass 3500 software installation problems on XP

I have downloaded the Software from Canon and have deleted all printer drivers, but after re-install it pops up at the end and says Update not installed? I have done this and removed all Canon software but the desktop manager 3.01 and can not seem to find where it is. I have Run a search of files to try to find it to no avail. Any suggestions? I have even gone into HKEY......w32x86 and deleted there. I have SP3 running XP Pro.
I have even gone so far as to get it to recognize the printer, but when going thru set-up wizard, it shows up but says that it is not digitally signed by Microsoft. I think if I can figure out how to remove the desktop manager 3.01 it will solve my problem, I'm not new to computers, but drivers always seem to be a pain. I am going to attempt a program recommended called robot drivers, I already have enough time in it I could have bought the customer a new one! Thanks for any replies, especially how to remove the "invisible" Canon Desktop manager 3.01!