As of last night, July 29, I had the exact same problem. All I did was start my computer, went to do a manual update so I could run a scan, and I got the red cross errors that my computer was not protected. Everything was perfect the day/days/weeks/months before, no new software or changes to system were made.
Clicked fix, everything went "green" again but reverted to disabled when I clicked update again. I also got a lingering message that I had never seen before after I clicked update, it said "checking internet connection" or something like that, it held there for a minute or so, then updated, then everything was disabled.
I called AT&T help (I have McAfee SC through ATT/SBC high speed), went through 2 first level techs. The first took virtual control of my PC, loaded the virtual technician, ran it, 1 error fix, 1 unfixable, ended up being my VS disabled. She went to VS config, clicked enable, it took and she said everything was fixed. I asked if she would click on update to test it again, she did and it went back to disabled. She said she had to refer me to 2nd level tech, but inadvertently connected me with another 1st level tech who went through the exact same steps (and had the same "playwritten" comments and responses). Same-o same-o with the second 1st level tech, who then put me on hold (again) and connected me with 2nd level.
2nd level tech sent me an email with a patch for update, that did nothing, ran virtual tech again, did some "ping" test from a DOS prompt, said I was good to go, asked him again to wait while I clicked update, it happened again, nothing was fixed, he said it must be my internet connection and to try again tomorrow. If not fixed, to call back (he said I'd have to do the 1st level tech routine again).
In all 3 cases, I asked if they were receiving similar calls about this type of problem or if they were made aware of any McAfee issues. All 3 denied, said I was the only one, ultimately I was told the problem was unique to me and must be my internet connection, suggesting I call my AT&T subscriber and get them to change my connection settings or something. Yet another wasted 2 hours with techs who I always seem to have trouble understanding as well due to strong accents, that's frustrating and leaving after 2 hours with no fix other than to try tomorrow. Seems like one suggestion they always give (but didn't last night for some reason), is to uninstall and reinstall the product...that seems to be a stock answer that puts the problem on you and your computer and not an overall software or IT issue.
Anyone know what or when McAfee is going to do about this? It's very apparent their update for 7/29/09 did it; I was updated through 7/28 (evening) with no issues, this all happend when I started my computer last night (7/29/09) and updated.