IE9 Text Size on WebPages

Following an upgrade to IE9 I've had problems downloading Adobe Flash 10.3 (now resolved) but irritatingly worse is that all text entry onto web pages eg username/passwords is so small you can hardly see it. Also the look of webpages is different (poorer quality)
I've reverted back to IE8 to try and resolve the problem but no success and not sure where to look to resolve it
Any suggestions?-is it a IE9/Vista problem

Welcome
Sounds like a a resolution
http://www.vistax64.com/tutorials/84291-screen-resolution.html

or

DPI Problem
http://www.sevenforums.com/tutorials/443-dpi-display-size-settings-change.html
for Seven and Vista

Thanks-have tried both these suggestions but no luck
The dpi change affected the size of text on desktop/web pages but the text size to enter id/passswords/user details on individual web pages remains tiny
The screen resolutions were as recommended by your link and made no difference
Could this be a virus? I ask that as, to download Adobe Flash, I had to turn Antivirus off as Adobe suggested. I have run a scan but nothing found

OK
Make a full anti virus scan, if this is already done. Download and make a full scan with malwarebytes. Be sure to update first.
If all is clear, go back a few days before the problem with System Restore
http://www.vistax64.com/tutorials/76905-system-restore-how.html