Testing Master page changes in Sharepoint can be a little tricky. I had a situation recently where I would view the master page and see all of my changes, a person sitting down the hall from me would see some of the changes, and a person across from her saw none of the changes – and we were all looking at the same page!
I checked browser cache, disabled output cache on the site, restarted IIS, restarted the computers, and restarted the servers (desperate), with no luck.
The Gotcha here is that it turns out that the CMS abilities of SharePoint extend even to Master pages. In order for everyone to see the same page, you must check in your new Master file, then Approve it by clicking ‘Approve/Reject” in the file dropdown in the Master Page Gallery.
What happened in my case was that I had created the initial new .Master file from a base .Master file and installed it as a feature (1.0 and Approved), I then checked that out in Designer, made most of the modifications and checked it in (v1.1, Unapproved). I later checked it out and made other changes and saved them but did not check them in because I wasn’t done (1.2 draft).
At this point, all three of us could view the exact same page and see three different layouts. I have no hard proof on exactly why this happened, but I do have a theory. Here goes: I was seeing v1.2 because I was the one making the changes and had the files checked out. The person down the hall saw v1.1 because she was an approver and was viewing the most recently checked in copy, presumably to approve them. The person across from her saw v1.0 because that was the most recently Approved version of the page. Once I checked in the files and approved them, everyone saw the same thing again.
This all makes sense but really catches you off-guard if you aren’t used to the new CMS mindset. Remember, if someone comes to you saying that two (or more) people are seeing different versions of the exact same item, the approval process for that item might be a place to start looking.