Hi Carl,
It could be due to 2 reasons :
1. Browser settings, check your browser settings.
2. Corrupted HTML files on the flash. Try to download the new IOS files with .tar extension and extract them and it should work for your.
I would suggest to use CNA (cisco network assistant) a free to use GUI tool for network management. You can download it from www.cisco.com/go/cna
HTH, Please rate if it does.
-amit singh