Thought I would give a warning about this.
I just upgraded today and found out there is an issue with Windows 8.1 and the mouse while playing games.
It is adversely affecting LotRO. Until today LotRO and my mouse working perfect.
After installing the 8.1 patch clicking my mouse buttons while moving in-combat causes the screen to jump. It suddenly jumps from normal view angle to looking straight down onto my characters head.
Playing LotRO is now very frustrating.
At first I did not know why this was happening, but I did some searching on the Web and there are many huge threads on gaming forums, such as WoW and Steam, about this issue.
There are some articles that discuss it and offer some possible workarounds but from reading the WoW thread it doesn't seem like the workarounds work.
I want to try the one workaround but I don't know which EXE file(s) to change. According to TomsHardware it might fix the problem by setting the games EXE file to run in compatibility mode for Win 8 or 7.
Which EXE file though? In the Turbine folder there are about seven different ones, all with different names, like: launcher, evoker, etc.
Here is the article (it only mentions mouse-lag, which I am not getting, but the most annoying and prevalent problem seems to be the one I am having with viewpoint jumping:
Windows 8.1 May Cause Mouse Lag in Some Games
By Kevin ParrishOCTOBER 22, 2013 3:40 PM
... a way to possibly fix the mouse issue is to right-click on the EXE of the game in question, go to Properties, go to the Compatibility tab, and check "run this program in compatibility mode for" and select "Windows 8." Also check "disable scaling of high DPI settings" and check "run this program as an administrator." This method may or may not solve the problem.