Jonathan, it shouldn't do that. Have you tried resizing the window? 

Also, try looking at View>Page style>Basic in firefox.

How recent is your Windowblinds? (post the information in the 'About Windowblinds' tab in the WB Config window, please).

Also, could this be a conflict in a Windows/Hebrew OS? Or in the view settings (try UTF 8). 

Working fine for me here too on FF4.

I'm having the same problem as Jonathan, and scrolling locks up entirely...

That's odds bodkin.

Might be helpful to know what extensions you both use.

and theses Add-ons :-

Adblock Plus 1.3.3
BetterPrivacy 1.49
FoxLingo 2.7.2
NoScript 2.0.9.9

Same problem here, title bar not skinned and I can scroll only with the mousewheel, but this happens only if firefox window is maximised.

Disabling Adblock Plus and NoScript makes no difference.  Did you mean uninstall them?  The scroll bar does not paint in the first window that is opened - if i open a second window, it almost crashes firefox.

Since installing firefox 4.0, my computer crashes when I am using the browser.

Unknown if this is being caused by the incompatibility.  I have placed firefox on my windowblinds exclusion list.

Your computer has a Windows Experience Index base score of 4
Your Windows Graphics Experience score is 4

WindowBlinds version : WindowBlinds 7.2 (build 301 - Windows 7 Edition) - 64 bit OS

WindowBlinds is installed correctly on this PC
WindowBlinds appears to be activated on this PC
(Dell S1909WX(Analog)) 1 is attached to Intel(R) G41 Express Chipset

Wblind.dll         2011/02/01 15:51:20
Wblind64.dll         2011/02/01 15:51:53
Wbsrv.dll         2010/08/09 13:03:56
SevenConfig.exe         2010/11/29 14:40:27
Wbload.exe         2010/11/29 14:40:35
Wbhelp.dll         2010/11/29 14:40:34
Tray.dll              2010/04/01 17:40:19
Wbload.dll              2010/04/27 10:10:25
Screen.exe         2010/06/07 15:10:43

I uninstalled all my add-ons but the problem did not go away....

I've had problems with FF3.6.xx locking up/crashing on attempting to open a 4th to 5th tab or so for awhile now, even after a complete uninstall and re-install of FF.  Same issue when I was using FF4beta10 (haven't tried later betas or the release version yet).  Appears unique to this particular notebook, which has had no add-ons installed except IETab 2.

FF3.6.xx has never locked up or crashed regardless of the number of open tabs on two other machines I have, one a notebook and one a desktop, both with IETab 2 and AdBlock Plus; the desktop also has NoScript.  Seems machine-specific rather than add-on specific to me.  Interestingly, the machine that has had the problem with FF crashing is the only one of the three to have had IE8 installed, and the problem only began after the IE8 install... scratches chin .

EDIT: Just remembered all 3 machines also have Back-To-Top installed.

Not sure that's the case.  Only one of the three machines has the problem but all three have Back-to-Top.  The only thing unique to the 'problem' machine is IE8.  Setups are essentially the same on the other machines otherwise (with minor variations in the two).

If your whole PC crashes when running FireFox4 then it is probably a buggy video driver issue.  FireFox 4 uses hardware acceleration for rendering and this means your video drivers are now doing more than before.

Which skin are you using?

I quickly checked WB on XP with firefox4 and I have not encountered any problems with scrolling.