Missing Data - ACID

["Andrew Lacey" <Andrew.Lacey () hsntech com>]

Hello group,
 
When I ran a query from April on ACID I found that the last 14 days of
the month were missing all data, 
 
Please note no filtering as all data from the 1st of April until the
15th was shown.
Then data is displayed from the start of May
 
Can anyone tell me where the data is held, is the data for each day held
in separate files? 
I would then be able to tell if the data has been captured/ corrupt or
not gathered.
 
What log files or processes should I check to diagnosis where the cause
was problem?
 
Thanks in advance
Andrew