<p>I've updated my TortoiseSVN client and now I'm getting the error when trying to update or commit to different repositories:</p>

<blockquote>
  <p>The requested name is valid, but no data of the requested type was
  found</p>
</blockquote>

<p>Any ideas on how I can solve this? Internet Explorer shows up appropriate URL just fine.</p>

<p><em>TortoiseSVN 1.5.3, Build 13783.</em></p>

This error being reported is a winsock one, rather than being particular to TSVN. From
Windows Sockets Error Codes
:
The requested name is valid and was found in the database, but it does not have the correct associated data being resolved for, e.g. an MX record is returned but no A record - indicating the host itself exists, but is not directly reachable.
It is strange that you can access the host via IE however. Is it possible that in TSVN you've specified a port number that isn't available on the remote host, and IE is accessing the host on port 80?