Windows can not check for updates

[#1]

Hi everyone,
I hope someone can help.
I recently moved to plusnet and since then the windows update icon says that windows can not check for updates.  Is there some sort of plusnet setting that I need to change to make this work again? when I manually check for updates I get an error message
I'm using Windows Vista if that's any help?
Thanks

[#2]

Can you post the error message - as a picture if necessary using the Additional Options and Attachments button

[#3]

the error code it brings up is 80070490

[#4]

Here's one possible cause, nothing to do with PN though:
http://windows.microsoft.com/en-GB/windows-vista/Windows-Update-error-80070490

[#5]

I have tried running the system update readiness tool which gave me the following log

=================================
Checking System Update Readiness.
Binary Version 6.0.6002.22441
Package Version 9.0
2010-10-02 12:56
Checking Windows Servicing Packages
Checking Package Manifests and Catalogs
Checking Package Watchlist
Checking Component Watchlist
Checking Packages
(f)    CBS Registry Error    0x80070002    Package_3_for_KB905866~31bf3856ad364e35~x86~~6.0.42.0        failed to get CurrentState
(f)    CBS Registry Error    0x80070002    Package_3_for_KB905866~31bf3856ad364e35~x86~~6.0.42.0        failed to get Visibility
(f)    CBS Registry Error    0x80070002    Package_for_KB905866_client_2~31bf3856ad364e35~x86~~6.0.42.0        failed to get CurrentState
(f)    CBS Registry Error    0x80070002    Package_for_KB905866_client_2~31bf3856ad364e35~x86~~6.0.42.0        failed to get Visibility
Checking Component Store
Summary:
Seconds executed: 4209
Found 4 errors
CBS Registry Error Total count: 4
What does this mean and how do I correct it?
I thought I may need to uninstall update KB905866 but I don't know how to do this as the update history has been cleared.
I also do not have the original windows vista cd/dvd ad it was pre-installed when I bought the computer so can not re-install windows

[#6]

A search would indicate that it is nothing to do with Plusnet
There are a number of solutions suggested mostly involving a repair install or a roll back to an earlier state.
This one however may be worth a try
This is to download the updates which fail direct from the Microsoft download centre and install them yourself - this may fix the problem
http://www.microsoft.com/downloads/en/default.aspx

[#7]

http://support.microsoft.com/kb/958044