DLU profile desktop timeout?

We're testing XPsp3 w/nc49sp5 & Zen7 running as an on-demand VDI VM in
VERDE (aka Win4Lin). Everything works, including DLU, but sometimes
during desktop load when logging in we get an error that the
H:\pathToWhereTheProfileIsStored\Desktop is not available and to check
the drive, etc, etc.

It completes the login, including mapping to H: and the rest with no
problem, again, very quickly. Once logged in, refreshing the desktop
produces the proper icons.

These VMs are very fast and it appears that the roaming profile
desktop is not delivered in time so it gets impatient. Is there a reg
setting that tells it to cool its jets?

Lyle