Application Error Explorer.exe after logon

After logging on to my Vista Business Edition the explorer crashes and
restarts.
When the explorer is loaded again i can work normally.

In the eventlog i get this:
Fehlerhafte Anwendung Explorer.EXE, Version 6.0.6000.16386,
Zeitstempel 0x4549b091, fehlerhaftes Modul msvcrt.dll, Version
7.0.6000.16386, Zeitstempel 0x4549bd61, Ausnahmecode 0x40000015,
Fehleroffset 0x00055bff, Prozess-ID 0x4cc, Anwendungsstartzeit
01c7dd908b35c14d.

Anybody out there who can help?

Thanks