These units usually ship with HP Sygate Security Agent or Symantec Endpoint Protection. If these applications have been removed, disabled (or properly configured, I guess), you might want to check the following:
1. WMI Support. The latest (Dutch) image from HP has built-in WMI Support, older versions may need the add-on (
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=12...);
2. DCOM and WMI Services. The DCOM Server Process Launcher and of course the Windows Management Instrumentation service must be running. By default, both are configured to start automatically, but it won't hurt to check;
3. Date and Time. Make sure the date and time on the Thin Client are correct;
4. Domain Membership. I'm pretty sure it's not necessary to add the units to the domain (and I'm aware it's a highly unusual thing to do), but if you don't you will probably need to add the account used for the scan to the local Administrators group of each unit. At the very least you will need to configure alternate domain credentials (
http://www.lansweeper.com/kb/workgroup.aspx). Note that even if you've added the units to the domain there's no need whatsoever to actually log on to the domain: you can still use the built-in User account to (auto)log on locally. There's a possibility you will need to disable the automatic machine account password change (
http://support.microsoft.com/kb/154501/EN-US/) if you add your Thin Clients to the domain, though the last post in this thread suggests otherwise:
http://forums11.itrc.hp.com/service/forums/bizsupport/questionanswer.do?admit=109447626+126452788452....
Because of the low Clockspeed (less than 1.000 MHz.) of the AMD Sempron Processor, Lansweeper will report that the hardware minimum requirements for Windows XP Professional aren't met. (The build numbers for Windows XP Professional and Windows XP Embedded are identical, so Lansweeper can't distinguish between them.) If you're a premium user, you can work around this by editing the "Not the hardware minimum requirements" report.
Hope this helps,
Roelof