[TYPO3-english] Troubles with rtehtmlarea on 4.2.5

[Sergey V.]

Dear list,
I worked with rtehtmlarea on typo3 v. 4.2.1 on one server (1). It worked 
normally.
I moved site to another server (2) - RTE is not loading there
I upgraded typo3 to version 4.2.5 on (2) server. RTE now is loading, but not 
saving text, i.e. I click "save", then RTE is loading and displaing only old 
information.
I tried also install dummy site on both servers. Results - the same as 
above.

I don't undestand why same configuration not working on different servers.
Please help me, where can I search and find (which sources), why RTE is not 
saving text?

Now I use tinyRTE (it is working on both servers), but I want to use 
rtehtmlarea.