Canon MP620 Loses Connection

Question

I have a Canon MP620 wirelessly connected to my Mac Mini, Leopard 10.5.8. I've had it for at least six months now with no problems, flawless printing and scanning. All of a sudden today I go to print, and nothing. I have changed no settings on the computer since the last print job a couple days ago and it's like the computer just doesn't "see" the printer. No error message, but when I open the print queue it says "Hold" and when I click on the Utility > Network it says "Communication Failed."
I did the usual: restarted the printer, rebooted the computer, several times, even restarted the wireless router, to no avail. So I started fresh, deleted all related files and broke out the install CD. Followed all directions to the letter and nothing.
I've repaired disk permissions, downloaded the latest drivers from the Canon site, still nothing. I've spent five hours on this now and and the frustration level is rising. (Naturally, when I was ready to call Canon Tech Support, it was a half hour after they closed and they're not open on weekends).
The other two devices that rely on the wireless router (iPod Touch and iPad) are working fine, FWIW.
When I run the Canon IJ Network Tool I get as far as testing the network performance. There are no bars at all and it says that it cannot test the performance, showing a question mark above the printer and router.
I don't know if this has any bearing on anything or not (if not, please don't laugh at a newbie's question), but earlier in the process of running the Network Tool, it shows a handful of area networks, mine being at the top of the list and having the strongest signal. It shows that my network is on Channel 6, and there is another network also on Channel 6. Could that be causing some sort of interference if, say, the other network is a new one or recently changed to Channel 6? I tried to see if there was a way that I could change the channel to an unused one, but couldn't find any documentation on how to do that.
Again, nothing has changed since I printed last. No setting changes and the printer and router are still about two feet from one another. Any suggestions?
TIA!
- Bob

Answer 1

On a lark, I tried printing from my Acer Windows XP netbook...and it worked!
So it's obviously not a problem with the printer itself, but for some reason, the Mac just isn't "seeing" the printer. The drivers are there, but when I go to print I get a "Communication Failed" message (from TextEdit). When I tried to print from Firefox, I got a 306 message, so they are presumably the same error.
On an aside, I don't know if this is related, but Safari isn't working. I don't use it too much anyway, but I launched it and when it tried to bring up the home page I got the following error:
Safari can’t open the page “http://www.apple.com/startpage/”. The error is: “Operation could not be completed. Operation not permitted” (NSPOSIXErrorDomain:1) Please choose Safari > Report Bugs to Apple, note the error number, and describe what you did before you saw this message.
I trashed the preferences, reset Safari, even trashed it altogether and downloaded it from the Apple site, all to no avail. I keep getting that error message when I try to navigate to a website.
After Safari wouldn't operate properly, and the ongoing printer communication errors, I ran a full virus scan with Intego's VirusBarrier X5 (all filters updated). No viruses (I didn't think there would be, but wanted to rule it out).
Any ideas...?
- Bob