Till, thanks for the link. But i got one problem:
1) After following the punto's steps, if I go into 'management' tab, it got stuck at 'loading folders...' in IE6. It says 'admin/inhalt_tree.php' line 311 object expected; I cannot see 'management' panel anymore.
2) However I didn't have this problem in Firefox;
3) I'm using ispconfig 2.2.11 on Fedora Core 5 x64.