SharePoint file uploading problem

Sometimes strange things happen after applying security updates to the SharePoint server. Recently a friend told me that after applying a security update, users in his company complained that they were no longer able to upload files to the SharePoint. If this happens to you, make sure it's not because of transaction log. Usually when transaction log is full, users get these types of errors. Also, run following command and it should solve the problem:
stsadm -o setsitelock -url http://yoursiteurl -lock none
lock types: none, noadditions, readonly, noaccess