You could start by telling us exactly what the problem is.
What is your OS ?
What were you doing at the time ?
What errors are you getting (suspect "usigetskin failed, etc.") ?
If So:
About the "usigetskin failed" issue, if the avast! repair does not solve it:
You will have to register ACTSKIN4.OCX
Follow the instructions:
Select START -> RUN...
Enter the following command:
If you have Windows NT or 2000:
C:\WINNT\SYSTEM32\REGSVR32.EXE ACTSKIN4.OCX
If you have Windows 95, 98 or ME:
C:\WINDOWS\SYSTEM\REGSVR32.EXE ACTSKIN4.OCX
If you have Windows XP:
C:\WINDOWS\SYSTEM32\REGSVR32.EXE ACTSKIN4.OCX
If you have Windows x64:
"C:\WINDOWS\SysWOW64\REGSVR32.EXE" ACTSKIN4.OCX
Press OK (or Enter).
A message saying that the file was successfully registered should appear...
For some reason, ActiveSkin (the 3rd party library avast uses for skinning) does not seem to be working on your system. As a workaround, we may disable skinning in avast - that should solve the problem. Program Settings, Common, and uncheck any option with skins mentioned (see image, avast-no-skin).
If you are unable to access the above you can do this manually. To do that, open the file <avast>\data\avast4.ini, look up the [UserInterface] section, and add the following entry: StartWithSkin=0