Editor problem - Pictures will not wrap around text unless I use html or TinyMCE

I have an editor problem across my blog sites. When users insert a picture it always stays on top even when using media manager to post it left aligned. My users don't know html and the only workaround that I had was to install Tiny MCe and edit the image there. My questions:
Is there a way to correct this bug? Is it a common problem?
I installed Tiny MCEditor as a local pluggin. Can I safely install it as a Global MU pluggin? Thank you for your input on this issue.