Pages needs to be refresh after each click

[embe1000]

Hello friends,

I'm completely new to Joomla having almost no idea about css etc...and as my web designer has no time in these days I ended here to ask 2 question regarding web site which I'm preparing:

- after each logging in into backend joomla stucks on a blank/white page and I must always press F5 to load it correctly. The worst thing is that this also happens in frontend and especially after I log in. I use ja_mageia template. the website is www.sky-xs.sk . Any idea what causes this? After I press F5 it works fine for some clicks but it happens again...and I'm crazy about that now.

- don't know if this is the right place for second question but i need to replace that picture (with China airlines logo) on that web site to flash animation but I don't know how. My webdesigner told me that I have to change template but I don't want to do so. P.S.:I have installed flash modules into joomla. Can you please let me know how to replace header1.jpg (which is the name of the picture) to let say header1.swf?

Many thanks for your help in advance, i really appreciate it.

Martin