Odd behavior with online table control

We have two redundant servers and 3 web clients. WinCC V6.0 SP4.

Yesterday, we had an odd behaviour. (screenshot attached, from the client, where one of the administrators of the plant is working)

He had printed the specific screenshot on 21-09-07 and 25-9-07. The odd is that the scrrenshot at 25-9-07 we notice at the dates 12-09-07 and 13-9-07 the letter "u". However, the screenshot that printed at 21-9-07 hasn't any "u" letters.

Furthermore, after this date (13-9-07) the values are different than those printed on 21-9-07.

The customer's was asking us how is it possible to have different values for the same flowmeter and for the same dates.

How that happened and how can we fix this so not to happen again?

Another remark : in the server the time's format is hh:mm (23:50) and on the client is hh:mm:ss:ms (23:50:00,078). How can we change the format to the client, so as to be the same with the server's?

Thanks in advance for your time