Dave, Taylor, thank you,

Tailor, you were quite right, it was registration problem. When I started the registration manager it said something about a lost data, I unregistered and reregistered (and also reinstalled between - just in case any other files were damaged) and now it is OK again (suprize - even MplabX works which did not work on this computer even when all other things were working.

Dave, I like some things in MPLABX but you are right, it has bugs so far so I used it but had troubles at the same time. What I like in it is long "Undo" chain, individual configutation for every project, also I use ICD3 and PICKit3 which I can not use in MCS. Loading existing .hex file is not convenient in MPLABX. After some troubles I decided to stop using MPLABX and wait for some time. Navigation in PBP code is better in MCS, this is for sure. I saw people use Pickit2 with MCS. Do you know if Pickit 3 can be used?

Gentlemen, thank you for help, Best regards,

Alexey