By default it opens up My Documents but you can change it to open your C Drive or other folders by the following:
Click Start, point to Programs, then Accessories, then right?click Windows Explorer, and click Properties.
Under Target field, which reads:
%SystemRoot%\explorer.exe, add to make the line read %SystemRoot%\explorer.exe /n, /e, /select, C:\
To display the Folders in the C Drive:
%SystemRoot%\explorer.exe /e, C:\
On the second topic about errors in Explorer you can run System File Checker to see if that fixes the problem:
Start | Run: SFC /SCANNOW
Insert the XP CD in the drive.
If that doesn't fix it try re-registering the DLLS:
1. Quit all programs that are running.
2. Click Start, and then click Run.
3. Type: regsvr32 urlmon.dll,
4. Click OK.
When you receive the 'DllRegisterServer in urlmon.dll succeeded' message, click OK.
If this does not resolve the problem, repeat steps 2 through 4 for each of the following files
(in step 3, replace Urlmon.dll with each of the file names below):
Shell32.dll (Windows XP and Windows 2000 only)
Don't forget to leave a space between 'regsvr32' and the .dll,
and don't forget to click OK