I am running Sims2 T&A, have 29 Hoods and 25 subhoods. Computer is running Windows 7 64 bit, AMD processor 2.7 GHz with 3 GB Ram on Lenovo Desktop. Don't think the computer is a problem because can run all my hoods and subhoods except one.
One of my early hoods was Pleasantview, with 34 households, 3 colleges La Fiesta Tech, Virginia Tech and Academie Le Tour with 24 playable Sims, 3 Downtowns - CORRAL GABLES (MY problem), Lake Shore and one just called Downtown. 2 households in Corral Gables, 2 households in Lake Shore, and 16 households in Downtown, one shopping District called Angola on the Lake with 7 households. Occasionally I've had some problems with Lake Shore but the major problem is Corral Gables. Many times I can't even get it loaded and then when I do it crashes soon after loading. I have the game installed on two desktops and one lap top. Played Lake Shore for some time last night on one of the computers but couldn't load it on the other.
Another problem was had shadows even thou I turned them off in the game, large square shadows of people. Went to userProps.xml and changed the default from 1 to 0. Have a feeling problem is related to my TV's and/or time. (there is one family in the main hood, Pleasantview, that crashes at 17:59, so have game time turned off in that house. Not the house because I moved them and still had the problem).
Any suggestions would be appreciated.

My guess is it's corrupted. Is this the Pleasantview that comes with the game or a cleaned up version? All pre-made hoods come already corrupted.
Have you tired running Hood Checker?

For the shadow problem, you just need to install the shadow fix: http://www.modthesims.info/download.php?t=569585

It is the original Hood. Other than one family with the 17:59 clock problem the other families are fine, and two of the sub hoods are fine. What if I just deleted the one bad sub hood or would it be best to leave it and just not play it.

Yes you can delete without problems unless it is a game problem then the main hood maybe lost.

It should move all sims to the family bin.

I would make a backup copy of the hood folder before deleting the sub in game.

Did you run Hood Checker? If you don't want to try and save anything then yes you can delete if you don't mind sims being tossed into the family bin.

17:59 (6:00pm) freezing or crashing is usually a corruption of the family tree, at that time all sims age one day and the game broadcasts that throughout the family tree. A&N has an option to switch that off which will enable that family to continue to be able to be played but that corruption will spread and you will lose that 'hood sometime in the future. To switch it off place a 'Heaven & Hell fairy' sculpture on the lot and a Girls gnome, the gnome will then have an option to 'Game Mod.../Lot.../Block.../Broadcast 6:00 pm Wants' which sets an attribute in the fairy sculpture so you can delete the gnome.
If you wish to use the HoodChecker let me know because I do have an updated version for A&N.

Would it help @Chris Hatch to rebuild the family tree in SimPE - deleting and re-adding the links?

Probably not, the family tree in SimPE is too vague and doesn't show what's happening with less direct relatives like uncles & aunts. You're more likely to create problems than fix them.
I don't know for sure why this corruption spreads, I suspect when grow up wants/memories are broadcast they're broadcast to close friends as well as relatives so as more friendships get made in a neighbourhood so the corruption spreads. If that is the case then the corruption needn't be in the family that's showing the problem but could be anywhere.