I think I saw a screen shot of this in a different thread, but I can't find it at the moment.

When there are strange display artifacts, I suspect a graphics driver incompatibility.

As a workaround, you could disable hardware acceleration of graphics in Firefox and in Flash (if relevant):

(A) In Firefox, un-check the box here and restart:

orange Firefox button (or Tools menu) > Options > Advanced > General > "Use hardware acceleration when available"

(B) In Flash, see this support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

Any improvement?

thanks for the suggestion but no luck. Can it be an issue with the new Version 26 and XP compatibility? The scrolling works fine on other browsers Scott

One of the headline changes for Windows XP in Firefox 26 was the ability to play MPEG media in Firefox's built-in video player instead of having to use a plugin. But if this affects pages without media, that probably isn't relevant.

Could you try disabling one other acceleration-related setting? This one requires a visit to the about:config preferences editor.

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste gfx and pause while the list is filtered

(3) Double-click the gfx.content.azure.enabled preference to switch it from true to false.

I can't recall whether this takes effect immediately or after you exit and restart Firefox.

seems to work OK after reboot - thanks