Í've just installed the SugarCRM version 4.2.0d. I sometimes get the The directory name is invalid erro on a blank page. It's not consistent, sometimes I see the page (for example roles management) and when I save or want to access it again I get that error message.

I'm running it on a share hosting with the following configuration:

operating systemMicrosoft(R) Windows(R) Server 2003, Enterprise Edition
mysql versionVer 12.22 Distrib 4.0.25, for Win32 (ia32)
perl version 5.8.4
php versionPHP 4.4.2

Any idea on what could be causing it?
Thanks!