Probably there are some objects which are larger at they seems to be. Take a look on them within the desktop client by enabling the draft-mode in the tab view. Now your surface should get a grid and the objects are shown with their real size - you could just grab the small black squares and drag them smaller.
Another cause might be invisible objects - hidden by any condition - which you could check within the sheet-properties.
I would now playing with the zoom-level of the browser and/or the zoom-level from QV in % as well as the various fixed screen-sizes if an adjustment changed anything. Also the use of a few different browsers might be useful to detect if any of them have issues or if the same happens to all.
If nothing worked I would check the hidden objects again - and also if there are any extensions within the application.
Best thing is to attach the app or another sample app that has the issue, so some of us can try it out in our environments to see if we can replicate it. The only other thing is what version you are running here, if it is not the latest SR of whichever major track you are running, that is the other thing I would suggest, update to the most current SR and see if the issue persists. Oh, one last thing, if you are using the IE Plugin client, be sure the client version matches the server version. That is all of which I can think.
If you are using Ajax Client, try clearing the web browser cache too, forgot about that one.
To help users find verified answers, please do not forget to use the "Accept as Solution" button on any post(s) that helped you resolve your problem or question. I now work a compressed schedule, Tuesday, Wednesday and Thursday, so those will be the days I will reply to any follow-up posts.