Critical Printing Problem Help

[Joe Lewis Wilkins]

Hi everyone,

Though this doesn't appear to be related in any way to LC, you people are my most reliable resource for some trouble shooting that has me totally baffled. 

I have some drawings that I have been using reliably for ages. Suddenly, with no apparent changes to any of them, or the application in which they have been created, the light gray fills are printing as a light green. Is it possible that a virus has caused this anomaly? Since my eyesight is so poor, I didn't even realize this had happened at first. I've discarded every other possible resolution of the problem. This transpired pretty much over night. Yesterday everything was OK. Today not so. I've restarted, but have not reinstalled anything yet.

I guess my question is: Is this the sort of thing that a virus or malware might be capable of doing? I've very careful with the kinds of things that I accept and open, but I hate running programs that protect like Norton, but I did accept Cox's Free MacAffee protection a day or so ago. 

TIA,

Joe Wilkins