SQL: System locks up and runs slow after performing simple DML record insert

Question

SQL Version:  2008 R2
I am having a serious problem.  I ran the following code to perform a simple table record insert which ran successfully.  However, after running this code I could no longer access the related table.  I couldn't run a query against it. 
I tried to delete all the records and that wouldn't work either.  When attempting to run any DML statements (i.e. Select * From vPCCertificateTypes) against this table SQL gets locked up and never returns anything and no error messages.  I have
to manually stop the query.  Now the entire SQL system is running slow.
Any help would be greatly appreciated.  The code I ran to originally insert the records is below.
Regards,
Bob Sutor
CODE: 
Begin TRAN
 INSERT INTO vPCCertificateTypes (VendorGroup, CertificateType, Description, Active, Category)
 SELECT HQCo, 'MBE', 'Minority-owned Business Enterprise', 'Y', 'Affirmative Action' 
 FROM HQCO
 Where HQCo IS NOT NULL
  AND HQCo <> 100
  AND HQCo <> 99
 IF @@ROWCOUNT <> 44 ROLLBACK ELSE COMMIT
Bob Sutor

Answer 1

The problem was an open uncommitted transaction against the table as you suspected.  I ran your code and it cleared the transaction.  In the past I would intentionally leave our the Commit statement and then if the transaction ran fine, I would
simply highlight and run 'COMMIT' and it would close the transaction.  Apparently that is not the correct approach.  I'll use your suggested code from now on.
Thanks for the help.
Bob Sutor