We've received one report of FreeTextBox having issues in IE8. We confirmed the behavior and found the fix as discussed in this thread on the FreeTextBox support forums.
If your users are running IE8 you can fix this issue quite easily by downloading FreeTextBox v3.2.4 from this page, and pulling the FreeTextBox.dll out of the Framework-3.5 directory (this assumes you are running .NET 3.5). Take that dll and overwrite the FreeTextBox.dll currently in the /Bin directory of your DotNetInvoice installation. Note: Please backup your existing FreeTextBox.dll before doing so in case you need to roll back.
Email us at support@dotnetinvoice.com if you run into any issues with this fix.
---
Rob
DotNetInvoice Support