[exim] Problem with exim and vexim

Hello,

I have 2 major problems with exim.

The first one is that I get many entrys to my panic log. These entrys
are all similar and look like that:

2007-06-19 08:47:58 1Hxpfh-0004RB-VB Failed to find group "" from
expanded string "${lookup mysql{select users.uid from users,domains
where localpart = '${quote_mysql:$local_part}' and domain =
'${quote_mysql:$domain}' and users.domain_id = domains.domain_id}}" for
the virtual_delivery transport

I don't really know where to find the problem.

The secons one is that after 1 week of service I get a meesage that too
many SMTP-Connections are open and the exim4 SMTP refuses to work. If I
restart exim4 that does not help. I have to reboot the whole server to
get it working again.

Any clues ?

Thanks,

Martin