I’ve also had problems installing 4.5.1 where it didn’t install the service properly and it would give this message each time. What you can do is uninstall just the service and install it again.
1: Go to a command prompt (Start, Run, CMD.EXE)
2: Change to your WDM Directory (CDProgram FilesWyseWDM)
3: Uninstall the service (RptStdSvc.exe -u)
4: Install the service (RptStdSvc.exe -i)
5: Manually start the service (RptStdSvc.exe -r)
If it works, try rebooting your XP machine and see if it still works after the reboot.