Looks like something on your system is interfering with the skin function.
1. Can you run it directly from C:\Program Files\Alwil Software\Avast4\ashSimpl.exe ?
2. If not try C:\Program Files\Alwil Software\Avast4\ashSimp2.exe ?
3. Try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow. Now try running as you did before or with 1 above.
You could try this if 1 above and the repair doesn't work but 2 does, although you don't say if you are getting any errors ?
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 XP/Vista:
C:\WINDOWS\SYSTEM32\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