Hi Ann - I'd *love* to take your advice, but...
(1) logged in as me, I can't deactivate. It gives me the "you must be logged in as an admin" message.
(2) when I do log in as admin, I can't deactivate as it gives me "cannot deactivate" error, code 255:255, which the only documentation I can find says that it's an error to do with having some other CS suite trial/software installed previously: which I have not, this is a fresh install.
What's the effect if I DON'T deactivate and then uninstall?
Okay, this turned out weird. Fixed now, but WEIRD. After the deafening silence on this forum, I went and did some reading on other threads and with other people having similar (but it seems not the same) issue. It seems that there could have been three different causes: here's what I did to fix things, I'd be fascinated if anyone with closer links to Adobe comes up with the technical explanation of why this turned out the way that it did.
(1) Install may need to be done as Admin, rather than standard user on a Mac
(2) firewall/proxy server maybe isn't allowing some anonymous callback from premiere to adobe to register presets/codecs
(3) something else weird involving registration... some people have had issues with time zones, of all things. see below.
What I did:
(0) Took everything off the school network and put on my home wireless network: no firewall, direct connection to internet.
(1) Tried Ann Bens's suggestion above. Was unable to deactivate software while logged in as Admin on my mac. Came up with error code 255:255 in the notification box, even though I never had a trial version installed on this box. This was the same error I got at school, so I'm tentatively ruling out proxy/firewall issues.
(2) Read the forums some more. I'm in New Zealand, it's currently daylight savings time (GMT +13) here. In http://forums.adobe.com/message/4007876, someone in NZ had a different but similar problem with registering/deregistering Premiere Pro software during NZ daylight savings time, and found that changing to ANY other time zone fixed their issue.
(3) Thought "what the hell", changed the time zone to Samoa (couldn't bring myself to do Australia...) and rebooted as admin.
(4) Successfully deactivated software, no error messages. Interesting.
(5) Uninstalled premiere pro. Rebooted as admin.
(6) Ran adobe cleaner tool. Found some scraps, killed them off. Rebooted as admin to be on the safe side (still on Samoa time)
(7) Installed Premiere, no issues at all. Registered, no issues at all. All preset settings present and correct, no issues getting AVCHD files.
(8) Changed time zone to NZ day light savings time.
(9) Everything still works.
Hm. Adobe, SOMETHING is wrong with the way your software is handling timezones and registration of codecs/software on Premiere Pro CS5.5. Seriously, does anyone have a clue why this might be happening?
So, solved. Shall I give myself a tick for "correct answer" and "helpful answer", given I solved my own thing with no help from tech support?
Just installed Master Collection CS5.5 last week, but need to install a 64 bit OS to utilise premiere so tried to deactivate, no luck. Googled error #255.255, some replies were around firewall settings, so created a rule to allow anything to *.adobe.com through, but still no luck deactivating. Took my work PC home so there was no firewall in the loop, still no joy. Tried reinstalling over existing install, no good. Just came across your post regarding time zones and thought "no harm in trying it"......and it worked!!!
Thanks for the advice, must mentally put that one away for a rainy day!