What do you have at this Registry Key,
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\Scripts\3
"IEFixedFontName"="Courier New"
"IEPropFontName"="Times New Roman"
"IEFontSize"=hex:02,00,00,00
"IEFontSizePrivate"=hex:02,00,00,00
The above are the values I have for Medium text size?
Try the No Add-ons setting if you have IE7.
You could try resetting Internet Explorer settings. (Help and Support article)
"If disabling add-ons doesn't solve the problem, try resetting Internet Explorer back to its default settings. This removes all changes that have been made to Internet Explorer since it was installed, but it does not delete your favorites or feeds.
Close all Internet Explorer or Windows Explorer windows.
Click to open Internet Explorer.
Click the Tools button, and then click Internet Options.
Click the Advanced tab, and then click Reset.
Click Reset.
When you are done, click Close, and then click OK.
Close Internet Explorer and reopen it for the changes to take effect."
Any later updates may also have to be installed again?
Some older articles might have some use for you. Read up about the way you can prevent web pages from altering your browser appearance.
Internet Explorer Text screwup
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Fixing Internet Explorer 6
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Screen size
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