Which version of Dreamweaver are you running and which operating system are you using?
Does an error message ever come up after the extension runs for a while?
What you can try is, with Dreamweaver and extension manager shut down, rename the configuration folder (the one the filecache file is in). This will have the effect of disabling the extensions that you have installed. Try removing and then re-installing DataAssist and testing it and then do the same with Security Assist.