Different browser versions and so on could all impact but most likely, your lists need some work following the upgrade. See Using RoboHelp 8 on my site where there is information about the impact on lists.
The Convert option means your output is in HTML rather than XHTML so the browser will render the page in a different way.
See www.grainge.org for RoboHelp and Authoring tips
Thank you very much for replying. The convert option seems to fix the problem and I will probably redo my lists later because I did not seem to be able to make any changes to them.
I am still puzzled why one PC running the 64 bit Windows 7 Pro is able to display all numbered lists correctly and the other PC running the 64 bit Windows 7 Enterprise using the same version of Internet Explorer is not able to display any numbered lists correctly. I looked around with all the options for Internet Explorer and they are the same. I also noticed that when I used Google Chrome and FireFox, the numbered lists are displayed fine. I also noticed that if all the online help files are saved locally on the PC that is not able to displayed the numbered lists correctly, when I display the online help, the numbered lists look fine. It does not work when displaying the online help from a server. If you know an option that might make the online help to work properly with Internet Explorer without deploying a new version, please let me know.
Perhaps you need to delete IE's cache and history.