OK, but my Windows 7 machine is currently down so I don't know if this option is available in Windows 7
Try going to Control Panel > System, click Advanced Settings, the under Performance click Settings. Click the Data Execution Prevention tab and turn off DEP for Internet Explorer. If it's not in the list, browse to C:\Program Files\Internet Explorer and select iexplore.exe to add it to the list.
Again, I'm basing this on Vista's help file, so it may be a little different in Windows 7.