Tag Logging not working

We have run a number of process cycles (it is a industrial Kiln) and found out that the tag logging is dropping chunks of history. At first It appeared as if the archive configuration was at fault, and maybe the data was being erased as time went on. However we found out that data from previous cycles were still in the HDD while new data were being erased.

The diagnostic file named WinCC_Sys_02 contained a lot of entries like the one shown below:

255,28.10.2014,16:16:23:718,1012301,4,,DELL-PC,CCWriteArchiveServer,[(null),242]failed to insert into TagCompressed with 0x80040E45(20,2014-10-28 14:41:35,2014-10-28 15:16:21

It seems as if the sql server instance was blocking the write attempts.

Any idea of what it is causing these behaviour?.

Any help will be appreciated as we have ran out of ideas (and time!!!).

the CCTlgCommonArchiving also contained entries like the one below: