Are you running any third party add-ons to WLM such as Plus! or Stuffplug? If so, please try disabling them. What version of WLM are you using? Are you on XP or Vista?
I've not heard of this behavior due to spyware or a virus, but it's not outside the realm of possibility. It can't hurt to do a complete virus scan with up to date definitions, and 2 separate spyware scans with different programs, also with up to date definitions (I like SuperAnti Spyware and Ad-Aware which you can get from
Filehippo.
I'd be curious to know if you use a different login on your machine, does it behave the same? Or is it JUST for your new hotmail.co.uk login that it does this. If it does the same on any login on your machine, I'd be far more likely to suspect a plug-in or malware.
Also, if you login on another machine, does it behave the same for you there? If your login behaves that way on any machine, it's more likely a WLM server issue of some odd sort and will likely sort itself out...eventually.
I'll wait to hear back, but this one has my poor little brain boggled. Perhaps the answers to the above questions can help us narrow it down.