My issue was two fold: connecting to Kies and upgrading to ICS.
I hope my posting will help someone as to how I was able to connect to Kies and subsequently upgrade my Galaxy to Ice Cream Sandwich. I have a Samsung Galaxy S2, SGH-i777 (AT&T) phone and I was unable to get it to connect to Kies. A Mac or Windows computer could see the phone as a USB device, but the Kies software could not. Kies crashes a lot with either Windows or Mac so I think we have many software quality issues.
I spoke with AT&T for a very long time and they could not resolve the issue. Because I've been trying this for so long the warranty ran out and the Insurance rep told me that I'm out of luck because the problem has been going on for such a long time. (Really?) Replacing the phone was not an option.
I also spoke with Samsung. (You may have to call several times until you get a knowledgeable person.) And they walked me through many things. Finally resetting the phone to factory defaults solved the problem with the Kies connectivity issue. However, I was not able to upgrade the phone. Kies stated that 2.3 was the latest available version.
After installing several apps that I normally use, I again attempted to upgrade the phone to ICS. A Samsung rep told me to try to force an upgrade through the Tools > Firmware Upgrade and Initialization menu. That didn't work either. The software could not connect with the phone. Also, the Samsung folks don't know anything about Macs which is what I use. The menu option that you need to force an upgrade is not available on the Mac version of Kies. I had to come up with a Windows 7 computer to accomplish the upgrade.
Here is what worked for me:
1) Reset the phone to factory defaults (Hold both volume keys when powering on)
2) Do not update or install any apps
3) Connect phone to Kies
4) Tools > Firmware Upgrade and Initialization
When I did that I was able to connect with Kies and upgrade the phone. Of course you must backup everything to a SD card or some other source because it wipes the phone.
The following link was helpful but not complete to help me solve the problem:
SAMSUNG