Calendar items disappear

Is this a personal calendar or a shared calendar resource? who else has permissions to this calendar?
Have you looked at the permissions?

It is a personal calendar and I've just looked at the server's event viewer and this is what I found there:

Event Type:      Error
Event Source:      MSExchangeSA
Event Category:      General
Event ID:      9153
Date:            17/10/2008
Time:            14:37:50
User:            N/A
Computer:      NBS-LON02-S01
Description:
Microsoft Exchange System Attendant reported an error '0x80072030' when setting DS notification.

For more information, click http://www.microsoft.com/contentredirect.asp.

Event Type:      Error
Event Source:      MSExchangeFBPublish
Event Category:      General
Event ID:      8213
Date:            17/10/2008
Time:            14:43:24
User:            N/A
Computer:      NBS-LON02-S01
Description:
System Attendant Service failed to create session for virtual machine NBS-LON02-S01. The error number is 0x80072030.

For more information, click http://www.microsoft.com/contentredirect.asp.

Event Type:      Error
Event Source:      ESE
Event Category:      Database Corruption
Event ID:      467
Date:            17/10/2008
Time:            17:58:17
User:            N/A
Computer:      NBS-LON02-S01
Description:
Information Store (5516) First Storage Group: Database D:\Program Files\Exchsrvr\mdbdata\priv1.edb: Index ?B6708?T668f+MQ67a6 of table 1-4E6A is corrupted (0).

For more information, click http://www.microsoft.com/contentredirect.asp.

Event Type:      Error
Event Source:      ESE
Event Category:      Database Corruption
Event ID:      447
Date:            17/10/2008
Time:            17:58:17
User:            N/A
Computer:      NBS-LON02-S01
Description:
Information Store (5516) First Storage Group: A bad page link (error -338) has been detected in a B-Tree (ObjectId: 1736, PgnoRoot: 1081) of database D:\Program Files\Exchsrvr\mdbdata\priv1.edb (1081 => 1084, 1700).

For more information, click http://www.microsoft.com/contentredirect.asp.

Event Type:      Error
Event Source:      EXCDO
Event Category:      General
Event ID:      8208
Date:            17/10/2008
Time:            18:01:35
User:            N/A
Computer:      NBS-LON02-S01
Description:
Calendaring agent failed with error code 0xfffffeae while expanding recurring appointments.

For more information, click http://www.microsoft.com/contentredirect.asp.
Data:
0000: 48 72 51 75 65 72 79 52   HrQueryR
0008: 6f 77 73 3a 3a 43 45 78   ows::CEx
0010: 70 53 74 61 74 75 73 3a   pStatus:
0018: 3a 48 72 49 6e 69 74 20   :HrInit
0020: 66 61 69 6c 65 64 2e 20   failed.
0028: 4d 61 69 6c 62 6f 78 3a   Mailbox:
...

There is literally tonnes of them there.

These events have stemmed more questions regarding your DC/ Exchange enviroement, but I think we can keep focus on the caledar problem for now. I suggest the following:

If you moved the mailbox in question to a different server/ Storage group, this process usually fixes core calendar issues. Try this simple process and let us know the results.

Could you please let me know when I can find more information about how to move the mailbox to a different Storage group (I cannot move it to a different server as it is a Small Business Server 2003, so it's the only one available)?

In the meantime I have used the solution I have found on the EE (accepted solution):

https://www.experts-exchange.com/questions/21983496/ESE-Error.html

The only thing is that after importing the pst file into the recreated account on the PC for some time on the PC on the local network I had a message from Outlook asking me if I want to use a Temporary mailbox that is on the server or Old mailbox that is on the PC (I decided to use the Temporary one). Now this message is gone on the machine on the local network but when I am using VPN on the PC at home and launch Outlook there, the message keeps popping up.

Anyway, I would be really glad to know how to move the mailbox to a different Storage group.

Kind regards,

Jay