Windows 7: When I press personalize it will show "explorer.exe unspecified error"

Everyone when i press personalize when i right click on the desktop it will show explorer.exe unspecified error.. and in control panel/appearance and personalization the icon "Themes" is gone.HELP!!!

I would first run an sfc scan to check any problem with system files
Start>type cmd>right click then run as administrator>type sfc /scannow>enter

SFC /SCANNOW Command - System File Checker

Would also run some virus scans

Need a bit more information than this. Did you recently delete any folders or files? Which ones?

Did you haven any recent hardware changes? What?

And most importantly, what are your system specs?

Last 2 weeks I upgrade my windows 7 starter to ultimate and then after i reboot it when i pressed personalize it will show "explorer.exe unspecified error"..

Operating System: Windows 7 Ultimate 32-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.120830-0333)
Language: English (Regional Setting: English)
System Manufacturer: Acer
System Model: AOD257
BIOS: InsydeH2O Version V1.14
Processor: Intel(R) Atom(TM) CPU N570 @ 1.66GHz (4 CPUs), ~1.7GHz
Memory: 1024MB RAM
Available OS Memory: 1012MB RAM
Page File: 1303MB used, 4708MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 32bit Unicode

Try doing a Repair Install

I dont have a installation disc.

Did you do this?

yes but still it wont work.!i already did it twice!

But have you run a virus scan? If so what software did you use and is it up to date?

My antivirus is Microsoft Security Essentials and it is up to date..