SRC Attachments periodically vanishing

Attachments are intermittently vanishing in Service Request Catalog (SRC) items - Excel spreadsheet attachments "drop off", although they are attached in the back-end.

This is an intermittent problem and it appears to happen with all SRC items which have attachments.

The issue is temporarily fixed by clearing the browser's temp files but not reliable and does nor resolve the issue permanently.

for IE8 (on the SOE):
1. Click on File->New Session
2. In the new session click on Tools->Internet Options then click on 'Delete' browsing history.
3. Open SRC (dsms)
4. Open one of the items with an attachment and it should be visible again.

This workaround seems effective and temporarily successfuly resolved the issue on IE8 and Chrome but the root cause of this is not known.