Cannot read the log file

Since a few days i get sometimes the following message in my notification mail.

This is the log message 24-11-2010

Incremental Backup CDEF Task completed successfully.
Description : Create Incremental Backup Archive
From: Disk 1, Disk 2, Disk 3
To file: "G:\Images\SBS2003r2_CDEF.tib"
Password protected
Compression: Normal
Description:
"Incremental backup"
Cannot read the log file

The strange this is, that it it not every day.
I got one incremental backup job which creates sometimes a proper log, but sometimes the above,

This is the log message 23-11-2010

1 Information 23-11-2010 23:00:04 The "Incremental Backup CDEF" operation started
2 Information 23-11-2010 23:00:08 Analyzing partition 0-0...
3 Information 23-11-2010 23:00:08 Analyzing partition C:...
4 Information 23-11-2010 23:00:08 Analyzing partition 0-0...
5 Information 23-11-2010 23:00:09 Analyzing partition D:...
6 Information 23-11-2010 23:00:09 Analyzing partition E:...
7 Information 23-11-2010 23:00:09 Analyzing partition 0-0...
8 Information 23-11-2010 23:00:10 Analyzing partition F:...
9 Information 23-11-2010 23:00:10 Analyzing partition 0-0...
10 Information 23-11-2010 23:00:10 Analyzing partition G:...
11 Warning! 23-11-2010 23:00:10 Priority changed to Low priority
12 Information 23-11-2010 23:00:10 Analyzing partition C:...
13 Information 23-11-2010 23:00:11 Analyzing partition D:...
14 Information 23-11-2010 23:00:11 Analyzing partition E:...
15 Information 23-11-2010 23:00:12 Analyzing partition F:...
16 Information 23-11-2010 23:00:14 Create Incremental Backup Archive From: Disk 1, Disk 2, Disk 3 To file: "G:\Images\SBS2003r2_CDEF.tib" Password protected Compression: Normal Description: "Incremental backup"
17 Information 23-11-2010 23:00:18 Pending operation 135 started: "Creating partition image"
18 Information 23-11-2010 23:00:18 Locking partition C:...
19 Information 23-11-2010 23:02:24 Pending operation 135 started: "Creating partition image"
20 Information 23-11-2010 23:02:25 Locking partition D:...
21 Information 23-11-2010 23:07:41 Pending operation 135 started: "Creating partition image"
22 Information 23-11-2010 23:07:41 Locking partition E:...
23 Information 23-11-2010 23:22:18 Pending operation 135 started: "Creating partition image"
24 Information 23-11-2010 23:22:19 Locking partition F:...
25 Information 23-11-2010 23:27:56 Pending operation 132 started: "Saving partition structure"
26 Information 23-11-2010 23:27:56 Pending operation 132 started: "Saving partition structure"
27 Information 23-11-2010 23:27:56 Pending operation 132 started: "Saving partition structure"
28 Information 23-11-2010 23:27:56 Operation has succeeded.

If i check the event log entries, i only see events of tuesday and not any other day.
Probably the log database is corrupt , is there a solution to start with completely new log files.

All backups are created succesfully, only the log entry fails.