Comment 6 for bug 303351

This seems to be a problem with upstream dns. In my case it is Time-Warner, possibly blocked or blocking... (too large list of IP's possibly..).
My ubuntu box at work works fine.

I'll file this with them later on, but though I should share my findings:

Example:

nslookup
> server 66.75.160.64
Default server: 66.75.160.64
Address: 66.75.160.64#53
> scs.msg.yahoo.com
;; Truncated, retrying in TCP mode.
;; Connection to 66.75.160.64#53(66.75.160.64) for scs.msg.yahoo.com failed: connection refused.

But if I change to another one of Time-Warners dns servers:

server 66.75.160.39
Default server: 66.75.160.39
Address: 66.75.160.39#53
> scs.msg.yahoo.com
Server: 66.75.160.39
Address: 66.75.160.39#53

Non-authoritative answer:
Name: scs.msg.yahoo.com
Address: 66.163.181.107
Name: scs.msg.yahoo.com
Address: 66.163.181.166
Name: scs.msg.yahoo.com
Address: 66.163.181.167
Name: scs.msg.yahoo.com
Address: 66.163.181.168
Name: scs.msg.yahoo.com
Address: 66.163.181.169
Name: scs.msg.yahoo.com
Address: 66.163.181.170
Name: scs.msg.yahoo.com
Address: 66.163.181.171
Name: scs.msg.yahoo.com
Address: 66.163.181.172
Name: scs.msg.yahoo.com
Address: 66.163.181.173
Name: scs.msg.yahoo.com
Address: 66.163.181.174
Name: scs.msg.yahoo.com
Address: 66.163.181.175
Name: scs.msg.yahoo.com
Address: 66.163.181.176

if you can't get your isp to fix the problem, short term you can just pick one of the ip's and set it in pidgin.