It crashes in the lspcs.dll - my guess is: LSP for CyberSitter? Try to look for newer version of this app. You may also try to send them some minidump files (in avast4\data\log\unpXXX.mdmp ) for analysis. Till they correct their code, it may crash in every application it loads itself. :-(
Edit:
As a workaround you may try to prevent cybersitter from loading into the WebShield process. To do this, edit the avast4.ini file, located in the c:\program files\alwil software\data\ folder.
Find the section [WebScanner] and add the line (or edit the one, if such exists there)
IgnoreLsp=Lspcs.dll
and restart the shield and then the whole computer as well.
You should also report this error to the CYBERsitter support team since they might probably fix their LSP plugin in some of the future versions.