In the 1st. question : too few parameters to know what can be happening, I'm afraid.
About the 2nd one, it can be interesting to use the "Search" tool while reading the manuals:
Glossary for PARK in the Pearl 2000/2004 manual
This happens to a fixture when its DMX address is taken by another fixture during a later patching session. The fixture must then be repatched.
Chapter 2.2 EDIT on the Pearl 2000/2004 manual
2.2.1 Changing the DMX address of a fixture
You can re-patch a fixture to a different DMX address or a different DMX output line. All programming is kept.
1> Press Patch (if you’re not already in Patch mode).
2> Press E [Repatch Fixtures].
3> Use the numeric keypad to enter the new DMX address of the fixture. If you want to change the DMX output line, press E [Select a DMX line] and choose a new output line by pressing A B C or D.
4> Press the handle swop button for the fixture to patch that fixture at the new address.
5> Press Enter to confirm the change.
6> Repeat from step 3 if you want to change other fixtures.
• If the new DMX address was already used by another handle, the fixture or dimmer on that handle will be "PARKED". All programming for the handle is preserved, but you need to patch it to a new DMX address using the above procedure before you can use it again. If you view the fixture patch as described above, the display will show "PARK".