Help needed about solving a DNS problem.

[nima]

Helle al !
I'm new to this group, I never had any problems with my DNS before...
So, I own some domain names, registered with gandi.net and hosted by 
myself on my server. The primary DNS is on my server using Bind 9 and 
the secondary is gandi's DNS.
I moved my server last week to a new ISP, and do my IP changed.
The DNS where changed to reflect this new IP. But some domain names are 
sometimes accessible and sometime not. How is it possible ? If the bind 
config was wrong, it would be allways unaccessible ?
Plus, some domains are allways accessible and have no problems.
I also have some domain names registered at OVH.com ant hosted like any 
others, and they have no problems. Is it a problem with gandi.net ?
Thanks for your help.
Nima.