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Not just for windows users.
Help. windows/apple. Former Enthusiast. (NOT affiliated with Apple Inc. [Thank God])
Symptom:
The Mac computer continually [every power-up, reboot, or when the program is ran] asks for permission for an application to access a keychain.

Symptom:
The Airport Network is not finding a Time Capsule Disk.
Possible Cause:
The base station is misconfigured, or corrupt.
Possible Cure:
Reset the Base Station, Softly:
Reset the Base Station, Brutally.
Reconfigure the darn thing.
1.) To reset the Base Station [either way], follow Apple’s instructions Here. [<- Click]
A good article describing the location of the reset button for your model, how to perform a soft or hard reset, and what the ramifications of the said reset would be.
2.) Assuming the above didn’t work; Please deposit twenty-five cents for the next half-hour.
IF; The base station is the only wireless access point:
The Airport Utility located in /Applications/Utilities may ask you to restore your previous base station settings. Click ‘Restore’ to automatically re-enter those settings; after the base station reboots, try the wireless connection again. If all else fails, reconfigure the base station from scratch.
IF; The base station is part of a network (multiple router / gateways):
Consider these potential issues;
• A newer “dual-band” base station has two ‘networks', one for older [WiFi B, and WiFi G (faster) access], and a separate one for newer [WiFi N (even faster, and with greater distance potential) access].
If older (non-N) devices aren’t a consideration, then the router / gateway placement isn’t a problem. However, if older devices which can only connect to older (B, or G) networks are present, they can slow the entire network down to B or G speeds.
• The more networks present, especially for B and G networks [neighbours, and possibly other devices such as wireless phones, or microwaves], the greater the chance of conflict [11 channels or frequencies available; N networks have 149], resulting in slower speeds, and / or connectivity issues.
• The environment plays a part in the distance of a network; distances are quoted as "line-of-sight" [unobstructed]; variations such as buildings [their construction; vent work location, steel surroundings, wiring placement], and airwave congestion may restrict the access to a network.
• Current Comcast / Xfinity ‘Dory’ gateways [SMCD3GNV] cannot have their wireless network deactivated and, as such, always occupy a frequency.
That being read, you may need to consider the placement of the routers / gateways to compliment one another without conflict.
Do you wish to extend the network, like a Wireless Distribution System (WDS)? Several links to help configuring exist for different configurations:
[with Thanks to ddavel]
Airport Utility Help
Symptom:
Mac sluggish [spinning color wheel, slow overall performance] after Lion (Mac OSX 10.7) installation.
Possible Cause:
A problem with or an incomplete OSX installation.
Possible Cure:
Please, as always, backup your hard drive before preforming the following.
1.) Close all applications, Reboot the computer; hold down the shift key after the reboot (bong) sound. [Enters Macintosh Safe Boot]
2.) Run ‘Disk Utility’ located in the /Applications/Utilities folder.
3.) Select the “First Aid” tab in the top of the center window:
Symptom:
Airport shows connected to a network, the computer has an IP address, but has no connectivity.
Possible cure:
Open 'System Preferences’.
Click ‘Network’.
-If the padlock icon (lower left of window) is locked, click it to enter your password.
Click ‘Location: ‘ and select ‘Edit Locations’.
Click the little plus sign to add a new location to the list.
-name the location (for example: Default).
Insure the new location is selected (currently in use).
The Cepstral voices will work with Lion (Mac OS 10.7).
Just re-install the voices.
If you experience an unbootable windows partition, short of reinstalling windows, some options are:
While starting the computer up, hold down the 'F1' key to get to the windows boot screen, allowing for a memory scan, and 'F8' to select the various "safe modes" to boot into.
The 'F8' menu also contains the option for the 'Last Known Good Configuration' in-which the machine (hopefully) was recently booted from.