What browser are you using?

One possible cause that I have noticed, if your hard drive is full and you receive the Disk Cleanup utility, this will affect your next visit.

The "Temporary Internet Files" (with Internet Explorer) will be wiped clean and ... Whalla, you no longer are recognized upon the next vist (or refresh). If you try this while on the site, upon refresh (after the utility is complete) your reminders are wiped out or reset.

If this is your case, I can offer no solution except the knowledge that this is the cause.

Just a thought, hope it helps.

Ross