" ... Macros can affct a Mac as well, as I understand it, and the last time trashing an infected email resolved a strange screen problem. ..."
There is no way a Microsoft Word or Excel malformed macro can cause screen problems. They simply don't have the ability to do it.
If all of the following is true:
The infected eMail contained an old Microsoft Word or Excel file,
You have Microsoft Word and/or Excel installed on the computer;
The version of Word and/or Excel will run on OS9 or earlier but not under OSX except via Classic;
You double-clicking the attachment which caused Classic, OS9.2 and Word or Excel to launch and the infected document to open;
... then the macro might have affected your old version of Word or Excel in an annoying but non-destructive manner. It cannot affect the OS, other applications, or your documents, and especially cannot affect the screen display whatsoever.
If even one of the above is not true, it's impossible for a macro to have any effect whatsoever on your OSX Mac. If they all are true, you can eliminate any threat by launching Word and Excel and disabling macro functions. You will then be invulnerable to them.
Do not confuse the sun going down with your need for sleep. The two are coincidental, not proof that one causes the other.
The Bagle worm affects Windows systems only, as will the the Kama Sutra worm. It's a good idea to scan for viruses and delete them, but only as a favour to Windows users. The cannot do anything to your Mac whatsoever.
CRTs can be affected by magnetic fields but LCDs cannot, so if you have an LCD screen it's not magnetic or electromagnetic interference (or EMI). Personally, I would insure the video card is well seated and the connectors are not loose. They are far more likely to be the cause than any virus, worm, or macro.
Exploit.IFrame.Gen is a vulnerability that affects users who use Microsoft Internet Explorer on Windows. That particular name is used by ClamAV while most other AV applications have different names for it (AV companies make up the names themselves and they are not consistent from one application to another, even though they may be identifying the same thing, the names vary). It is a backdoor affecting Windows systems only; it cannot be the source of any problems on your Mac.
I think you are right to have your AV application clean your eMails when it finds a problem, so that you don't spread them to others who might be affected if they run Windows, but aside from that, forget about viruses and malware completely, because they are definitely not the cause. You would be better off trying to find the real issue rather than chasing ghosts; "fixing" these eMail attachments cannot be the solution because they cannot be the problem.
