You should have entered the password for XPMuser twice when you setup XP-Mode. It even had an option to have the OS remember it. If you think you left it blank, try this:
Turn off/shutdown the vm.
Open its settings, in Integration Features section, uncheck the checkbox that says automatically enable at start up(similar to that). click ok
Now boot the vm. At the login prompt, enter user name as (the xpmuser as displayed in the setup wizard), and hit enter (password blank), this should log you in.
Now, open command prompt, and execute "net user (username) (password)", if successfuly, your new xpm user password is reset to (password), if you wish to change the whole profile, you can just add a new user account and make it a member of Administrators group.
Now, open settings, go to "Credentials" page, and delete credentials. ALso, now go to integration features page, and enable "integration features at startup" checkbox.
Shutdown vm. (if you like it quick, just kill "vmwindow.exe" process in taskmanager)
Start the vm again, it should prompt for credentials, and you can enter the newly set credentials, and do remember to check the "Remember Credentials";