Today, I had a user contact me regarding testing they were performing against their SharePoint Team site. They were no longer able to logon as another user. When I went to see their computer I noticed three things:
1) Ribbon Tabs are too small
2) Ribbon Tab text is truncated
3) User’s Name and drop-down menu were missing from the Ribbon.
After a quick search I found a Microsoft Support Article with my exact issue.
Internet Explorer 8 is zoomed in past 100%.
The solution was quite simple. Open the View Menu, go to Zoom, and select 100%.