iCal gone wild!

I'm going nuts here. Have been using iCal without a hitch for months, but now suddenly it's gone haywire. Whenever I add an entry to iCal on my MacBook (2.4 Ghz; Safari 10.5.6) it just disappears. Not sure how long it takes to vanish but it's more than a few minutes. This problem affects entries in all different colour categories.

The entries do NOT disappear:

1. When I close the iCal window.
2. When I quite iCal.
3. When I allow Mobile Me to sync on its usual schedule (at least on the first sync, which I've checked).
4. When I manually sync Mobile Me (I have an iPod touch and iMac - Mobile Me has only ever worked very unevenly for me).

The entries just seem to disappear on their own, over time. This afternoon, I added four entries. They remained in iCal for somewhere between one and two hours. I began to think the problem had fixed itself - until all four vanished.

The entries that I put on my Macbook appear on the Mobile Me homepage iCal calendar. But they also disappear from there.

Entries I add to iCal on my desktop never disappear.

Any suggestions on how to fix this?

It's a total nightmare since my whole life is organized via iCal.

Many thanks!

iCal gone wild

Maybe you have your delete events set to a short time frame. To reset:
Click on iCal next to the apple
Click Preferences
Click advanced - third box down sets auto event deletion