Yahoo Webmail - problems accessing older messages in inbox?

I can't access messages in my inbox older than 6th October 05. Yahoo
mail seems to pause, then comes up with:

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We didn't understand your request.

The request sent by your browser was missing some information. Please
try again.

If the problem persists, we suggest that you close all browser windows,
relaunch your browser, and log into Yahoo! Mail again. If you still
have problems, please contact Yahoo! Mail Customer Care.
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A week or so back, it was doing the same thing with some of the older
messages in my drafts folder. The problem went away after a few hours.

I've tried this with both IE and Firefox.

Anyone else had the same error messages?

Andy