Well, have had no issues before leaving Lydia using the "wait here" command and going off to do other things, this time using that command in your assigned room in the College of Winterhold has caused my playthru to lose Lydia...shes gone, missing...she hasnt wandered off, she hasnt returned to my house in Whiterun or to Dragonsreach...the game simply doesnt load her in the location she was left

any ideas??

Followers will leave you after waiting a few days or so. You can try waiting a few days then going to your house. The game may have ate her like so many books. If so load a past save. Can you use other followers or is she still following you?

I'm not sure how related it is, but I had a weird thing happen in Winterhold with Lydia. When the magic nodes things were invading the town, when the fight was over, Lydia had become a follower of on the College mages. When I went to swap inventory with her after the fight ended, it listed her as "So and so's Lydia" much like when they conjure something and it says "So and so's flame atronach" and I could not start dialog with her. Not sure what was gong on, I fast traveled away and came back only to find a pile of ash in the town street that held all the inventory I had given Lydia. I ended up reverting to an earlier save.

not tried to have anyone else follow me, and have no saves before i had her wait for me in my room at the college...going to carry on and see if she re appears at my home in Whiterun...not impressed that this has happened, if its just the game code forgetting to load her in the location she was told to wait so now she has gone for good Bethesda will look more crap in my eyes then they already do

Thanks for the replies

EDIT: Well tried to have someone else follow me, but they just say I already have someone following me, so brilliant...game broken so cant have followers anymore

Mmmh.. this is not a bug.. She was more than likely killed, and resurrected by a fellow wizard..

How long did you wait..? (in game time) +/- 72 hours should dismiss her..
Edit: there are also quests which forcefully remove your current follower.. (companions for one..)

Ahhh... I hadn't thought of that. Yeah, I bet you're right and that's what happened. Thanks for clearing that up, that had been bugging me.

"So-and-So's Lydia?" definitely reraised after dying, as Thorgal noted.
The issue really is, why doesn't his game "know" she's dead?
The lesson: keep more save files, especially right before jumping on a quest, especially a named quest as they tend to have more going on and more likelihood of problems occurring.
As a footnote, I may have just lost Stray Dog under very similar circumstances. Still have to go back to where I found him to see if he went back there.

I think the most important thing about this game (or any others ) is to save aggressively. I keep a serial of saves, and then when it gets around 100 or more, I just go to the xbox and copy a few main saves, delete the rest, then move the copied ones back. (This requires multiple save devices of course). Now with the cloud, I suppose many more could do so.

But seriously, save save save. This game even eats its own saves sometimes.