I will have to leave Mr Papa to respond to any Windows/IE specific issues although currently we have no other outstanding reports of problems so I do tend to the belief – understandably – that this is a local environmental issue with your site.
The CSS and JS cache will not effect any data as such. It is not a data cache. It simply combines all of the forum CSS and/or all of the forum JS into one single file to make load times quicker and to avoid the particular issue with older IE browsers. If it can work on your site it really is worth using.
However – there are some environments where the server will not allow its use and we still have to find out quite why that is. I would try it as you will find quickly enough iof it works for you and of it does not is is just as quickly disabled again. And of it does work for you it might just be what the IE8 user needs.

