In IE, some letters are replaced by squares.

[bifruncated]

In IE, and sometime in OE (when, I believe, viewing an HTML communication), some of the alphanumeric characters are replaced by squares. At least in some cases, but, I believe, not all, the
Square appear on a line that is a link. [The Tech Support Forum site so full of line of squares as to make it very difficult to use.]

All actions are in English.

I am running Windows 98 on a self-assembled system that is based on an MSI K7N2 Delta-ILSR motherboard with an Athlon XP 2500+ CPU and 512 MB of RAM. The video card is a Matrox Millennium.

The problem is new, i.e., the system did not previously display this behavior.

I am using a fully patched IE 6. Tools|Internet Options are set as follows:
Security Tab: Internet Zone - Medium; Localinternet - Medium low;
Trusted sites - Low
Privacy Tab: Medium
Advanced Tab: Defaults

ZoneAlarm Pro 5.X is installed but the problem also occurs when ZoneAlarm is not running.

Spybot Search & Destroy is on the computer but the problem occurs when it is running and when it is not running.

This is also true for Norton SystemWorks 2003 AVG Anti-Virus

I have regressed IE 6 to IE 4 and re-upgraded to IE 6 with all current patches. This has not helped.

I have downloaded and installed Lucidia Sans Unicode.ttf. This has not cured the problem.

In IE View|Encoding, I have tried selecting Western European (Windows), Western European (ISO) and Unicode (UTF-8). None of these selections cure the problem.

I have no doubt that the problem is due to something I have done, rather being a hardware problem. I do edit the Registry and delete files I think have no purpose.