reformatted macbook & now it wont connect to iMac airport if it has a password?

pretty much covers it.. ive looked everywhere for an answer but it seems quite a bizarre one?

the macbook was connected via internet sharing on the imac ( via airport ) before i reformatted it today, and since then it just gives the notice 'connection timeout' whenever i try to connect when it has a password.

if i remove the password it will connect, if i change the password it wont, ive tried restarting both computers repeatedly, resetting various things. etc

my iphone can still connect to the imac ( with and without password), and the macbook can connect to other open networks so it cant be a hardware problem...

ive looked into posts that say change the channel but a, i dont think thats appropriate because it can connect if it hasnt got a password atleast...?!?! and b, well i couldnt find out how to do if your sharing it internaly ( ie internet sharing not base station) but note there are about 10-15 other networks in range..

both are running the latest versions of airport aswell both snow leopard. imac is a 27' i5 quad core macbook is a first release unibody 2.4ghz..

id love to get this sorted because i usually use teleport over the two of them and i cant unless theyre connected! noooooo ( and i only have one access point/ no hub so i cant just run them both wired or anything... )

never had a problem with it connecting before now!!

anyone have any ideas?!! any help much appreciated.

thanks. tom

okay i fixed it..

after relentless trying.. a combination of:

changing the local computer's name ( the imac),
changing the wireless networks name ( via the imac's airport)
changing to channel 11
going to a 128bit encription
changing the password again
turning the wireless off and on again

(all in one go)

lead to the macbook connecting instantly

( i had tried various combinations of the above before... but not all of them in one go )

so i thought id put this up here for anyone else to find if they have the same problem, as this is where i come if i ever have a problem and this is the first time ive had to post in the 5 years i've owned macs.

<3 x