OEM not working after windows patch KB2661254

See the following for more details:
http://blogs.technet.com/b/pki/archive/2012/07/13/blocking-rsa-keys-less-than-1024-bits-part-2.aspx
The above update will block the use of cryptographic keys that are less than 1024 bits. OEM uses a cryptographic key of 512.

The above article shows a workaround as follows:

1. open a CMD prompt,

2. enter the following command:
  Certutil -setreg chain\minRSAPubKeyBitLength 512

Alternatively, use Firefox instead of Internet Explorer.

SID_XDB service and SID_XPT Service 

In oracle 10g, when you check the listener service, you may notice two particular services registered:
[ccbqa] /orasw/app/oracle/admin/ >lsnrctl status|grep ccbqa
Service "ccbqa" has 1 instance(s).
  Instance "ccbqa", status READY, has 1 handler(s) for this service...
Service "ccbqaXDB" has 1 instance(s).
  Instance "ccbqa", status READY, has 1 handler(s) for this service...
Service "ccbqa_XPT" has 1 instance(s).
  Instance "ccbqa", status READY, has 1 handler(s) for this service...

ORA-01200

Sometimes when you try to start a database, you may get ORA-01200 error like:

ORA-01122: database file 8 failed verification check
ORA-01110: data file 8: '/bitest/oradata/bitest/cists02.dbf'
ORA-01200: actual file size of 64000 is smaller than correct size of 416256 blocks



The best solution is restore if you have a backup.
However if you don't have a backup, you can try to make the datafile have same block sizes registered in the control file to cheat oracle, but you may face data loses.

Steps as below (Caution: use at your own risk!!)