Hi voktv, welcome to the community!
1. Support team should provide detailed information on the issue.
2. I want to move VM from one esxi 4.1 host to another one with the minimum downtime, don't have SAN, is Quick Migration the best solution?
As the second option to Quick Migration I’d recommend you to use Replication job
followed by planned failover
.This should be the best solution with minimum downtime.