[Carlo Lazzaro]

Fabian:
it's hard (for me, at least) to comment any furher without seeing what you typed (-xtset- included) and what Stata gave you back (as recommended by the FAQ). Thanks.

[Carlo Lazzaro]

Fabian:
this thread http://www.stata.com/statalist/archi.../msg00335.html may help you out in explaining what happened to your SEs when you invoked -nonest- option after vce(cluster).