Hi Ken,
To check the control I used the snippet you supplied and this worked ok but this was within a seperate web applicaiton to where we are having the issue.
to give some more detials on the issue;
We are using the control within a SharePoint 2010 webpart. The control works 99% (once or twice we have had the error) of the time on mine(windows7 ie8) and Mats(windows7 ie9) machine .
On machines which are Windows XP and IE7 we get the stated error on every attempt.
Also firefox on my machine gives the following error:
The security validation for this page is invalid. Click Back in your Web browser, refresh the page, and try your operation again.
Chrome works
Are there differences between how the browsers and/or the OS handle this type of authentication..?
My next step is to create a sharepoint 2010 webpart with just the cutesoft control on and see if this error occurs as soon as its ran within a SharePoint Enviroment.
Any information on why it would work on some set ups and not others would be very
helpful.