My wireless system has worked flawlessly for 3 years. My Linksys wireless router reset itself to default settings this week (due to power cut) so I had unsecured network for a few days. My internet provider came out today and updated firmware etc and reprogrammed it to the secure settings it should have. Now my iMac (10.4.11) sees the network but will not connect. Strangely iBook (10.5.5) and iPhone are working perfectly. The iMac recognised and connected fine to the unsecured network right up to when the tech man came. The Airport dropdown menu showing my network name does not have a padlock beside it on the iMac, but the padlock is there on the iBook. I have tried entering the router password manually but it says it is the wrong one. It is definitely the correct password. The whole system here is wireless (i.e. broadband is beamed wirelessly from a mast on a nearby mountain). In a few days I can take the iMac to another location to test it out on "conventional" cabled broadband with a wireless network in the house. I have tried the usual things, the only thing I cannot do is physically get to the router itself as it is in the loftspace in the house, but I can switch it on and off - but only by cutting the power supply to it. Any suggestions really welcome. My system was not actually broken but now it sure is. Grrrrr.