Error establishing a database connection + other questions

[#1]

Hi,
my site has been migrated over but I can't get access as that error appears.  I can log into the Control Panel and I have initialised PHP Admin and can see the database - which looks populated. 
I've checked the server, db name, user name against wpconfig.php and they are correct - not sure how to check that the password in wpconfig.php is correct though.
My domain is www.eyemagine.co.uk which I have updated in the DNS settings as follows:
eyemagine.co.uk. a 91.136.8.9
www                 cname eyemagine.co.uk.
Any ideas?
Other questions:
1) In the control panel I can manage ccgi.USERNAME.plus.com  ; cgi.USERNAME.plus.com ; eyemagine.co.uk ; ccgi.eyemagine.co.uk . Which one do I use - does it matter?  There's no DB against eyemagine but there is for ccgi.
2) In phpMyAdmin it shows a warning "Your PHP MySQL library version 5.1.70 differs from your MySQL server version 5.5.28.  This may cause unpredictable behaviour" - is this likely to be an issue?
Thanks
Andrew

[#2]

Quote from: coolj

1) In the control panel I can manage ccgi.USERNAME.plus.com  ; cgi.USERNAME.plus.com ; eyemagine.co.uk ; ccgi.eyemagine.co.uk . Which one do I use - does it matter?  There's no DB against eyemagine but there is for ccgi.

They all point to the same physical server space however they can have different instances of some of the other applications like Analytics etc. I'd suggest you keep everything under your main domain to save confusion.

Quote from: coolj

2) In phpMyAdmin it shows a warning "Your PHP MySQL library version 5.1.70 differs from your MySQL server version 5.5.28.  This may cause unpredictable behaviour" - is this likely to be an issue?

No.
I'll take a look at your other problem now...

[#3]

Thanks Bob.
I notice that it seems to be working now so thanks for sorting out what the problem was.
Regards
Andrew

[#4]

Yep, should all be good now