XP SP2 PC will only use broadcast/NetBT, not DNS

[Steven]

Hi all,

I'm trying to troubleshoot a problem on the in-laws PC where most
windows applications won't resolve Internet DNS names. Here's an
example of the symptoms I'm seeing:
- pinging an Internet DNS name fails on name resolution
- web browser won't resolve names
- using the command line nslookup util does succesfully resolve domain
names
- connecting to Internet resouces by IP address works fine.

Using Wireshark I can see that even when trying to resolve obviously
non-local names, the PC is broadcasting for an IP rather than going to
DNS, except when using the nslookup tool, which does do a DNS lookup
The IP configuration has the router IP as its DNS server.

Any ideas? Thanks in advance for any clues.

[beLIEve]

Have you checked your "hosts" file and see if it's contaminated?

[Steven]

Yes. the hosts file is empty (apart from localhost)

I'm just trying a Service Pack update in case this fixes it (it was on
SP2, I'm trying SP3). I got an access denied error after it backed up
all the files and registry. I am logged in with an Admin account.

I tried checking the DLL files previously and noticed that
dnsrslvr.dll has several copies in the system32 dir. (eg Copy of
dnsrslvr.dll, Copy (2) of dnsrslvr.dll etc) which makes me think that
they may have had a virus issue in the past. A scan with Trend PC-
cillin doesn't find anything though (though admittedly the signatures
will now be quite out of date as they can't connect to the Internet)
and I suppose viruses once present can coneal themselves.

Thanks for the suggestion, grateful for any others,

[beLIEve]

Try this: http://www.viruslist.com/en/viruses/encyclopedia?virusid=21782844

Otherwise, try boot up in Safe Mode and place a good copy of
dnsrslvr.dll into C:\Windows\System32 and any other directories that
contain that file.

If this doesn't work, attach the hard disk to another good computer
and do it from there. I wouldn't do any virus scanning this way
though, in case it deletes off important files and prevents XP from
booting up later. Once you're done fixing the file, reattach the HDD
back to the original computer, do a full virus scan before you install
SP3