Try to disable hardware acceleration.

• Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

• https://support.mozilla.org/kb/how-do-i-upgrade-my-graphics-drivers

Thanks cor-el, un-ticking the "Use hardware acceleration when available" check box, solved the problem straight away!

I will also look at my graphics drivers now for good measure.

My current line up is: Intel(R) G45/G43 Express Chipset

Memory type 2 Driver version 8.15.10.2302

As cor-el suggested in the e-mailed advice, I hope that this fix also makes someone elses day!

As a newby I did not click on 'Solution chosen', to show solved. Can an administrator do that for me please as that button is now out of reach, thanks.

Just thought that I would add that the hardware acceleration problem still exists for Firefox version 11.0 with the latest graphics driver update: Intel(R) G45/G43 Express Chipset Driver version 8.15.10.2413.

I had trouble installing the update following the Intel instuctions to the letter but got there in the end. If others are struggling with the Intel driver update instructions it may be helpful to say that my install worked afer I put the Win7Vista_64_151717.exe program in the Windows Temp folder and right clicked on the program to select 'Run as Administrator'.

CPU details: Intel Celeron E3300 Cores 2 Threads 2 Name Intel Celeron E3300 Code Name Wolfdale Package Socket 775 LGA Technology 45nm Specification Intel(R) Celeron(R) CPU E3300 @ 2.50GHz Family 6 Extended Family 6 Model 7 Extended Model 17 Stepping A Revision R0 Instructions MMX, SSE, SSE2, SSE3, SSSE3, Intel 64 Virtualization Supported, Enabled Hyperthreading Not supported Fan Speed 1005 RPM Bus Speed 200.0 MHz Rated Bus Speed 799.9 MHz Stock Core Speed 2500 MHz Stock Bus Speed 200 MHz Average Temperature 37 °C Caches L1 Data Cache Size 2 x 32 KBytes L1 Instructions Cache Size 2 x 32 KBytes L2 Unified Cache Size 1024 KBytes

Operating System MS Windows 7 Home Premium 64-bit SP1

Motherboard Manufacturer Acer Model EG43M Chipset Vendor Intel Chipset Model G45/G43 Chipset Revision A3 Southbridge Vendor Intel Southbridge Model 82801JR (ICH10R) Southbridge Revision 00 System Temperature 34 °C BIOS Brand American Megatrends Inc. Version P01-A2 Date 08/11/2009 Voltage CPU CORE 1.072 V MEMORY CONTROLLER 3.040 V +3.3V 1.520 V +5V 5.080 V +12V 12.032 V -12V -4.480 V -5V -13.376 V +5V HIGH THRESHOLD 5.053 V CMOS BATTERY 3.216 V

Yes I have spotted that two voltages do not match up! I will ask the shop where I bought it from about the -5v and -12v apparently being transposed on the sensing side.

The problem is specific to Firefox as my other programs and my only other browser: I.E. version 9.0.8112.16421 do not get the undisplayed menu elements stuck to the Windows status bar and lower bar of the active open window.

It looks to me that while menus get displayed correctly in the visible area that they are intended to, they just deploy to their full extent but are hidden by being overwritten by other elements in front of them in the 'active window' but when it comes to the lower edge of the active window and the status bar at the bottom of the screen, the 'hiding regime' no longer applies as the surface rules have changed. I have seen references to cairo surfaces but that is above my head!

The desktop surface below the active window, in the line of fire from a long menu list, was also written on but I could do a manual 'wipe' by dragging the active window down and back up again to 'wipe' fragments off the desk top surface! I missed that bit from the original post.

I tend to have large menus so I see the problem. People with small menus will not have the hidden portions of them crossing active window boundaries and the status bar at the bottom of the screen.

Fortunately, turning off the hardware acceleration is a good temporary fix and is easily done, as explained by cor-el.