Forefront Protection 2010 for Exchange Errors 7009 5314 on Windows 2003R2

I've got customer with:

- Exchange 2007 with the latest updates installed on 2 CAS/HUBs on Windows 2003 R2 and 1 CAS/HUB on Windows 2008 R2, also two clusters (one mailbox, one journaling);
- Forefront Protection for Exchange with Rollup 4.

Until April everything worked perfectly. Now there are many errors:

Event Type:       Error
Event Source:   Microsoft Forefront Protection
Event Category:               Health Status
Event ID:             7009
Date:                    2013-04-17
Time:                    08:39:20
User:                    N/A
Computer:         cas-hub-01
Description:

None of the antimalware engines selected for transport scanning have been initialized.

Event Type:       Error
Event Source:   FSCTransportScanner
Event Category:               Scan Error
Event ID:             5314
Date:                    2013-04-17
Time:                    08:39:20
User:                    N/A
Computer:         cas-hub01
Description:

Could not initialize Spyware Scanner properly.  As a result the system will not function.  Please check the Antispyware engine and signatures.

These errors affects only CAS/HUBs on Windows 2003R2, there are not present on Windows 2008R2. If I disable antispyware scan then without restart of Transport Service errors disappears. If I enable it again errors appear immediately. Of course Antispyware engine and signatures are updated.


The biggest problem is with queue - e-mails are not processed during these errors.

When the traffic is lower then errors don't appear or appear with very low frequency, during higher load, mass mailings e-mails are waiting in queue and are not processed.

Errors always appears in pairs. On low traffic - one pair of errors per few minutes, on high load two to three pairs per second.

Now I must investigate the real problem or some kind of sollution.