I had a very worrying issue today where scripts would not be loaded on Purchase Orders. 100% sure client scripts were not loaded, not sure about user event and did not get to test other record types. The issue occured on the browser Firefox Developer Edition (Adblock Plus add-on installed). They were running normally on the same browser in the Sandbox account, and on both Production and Sandbox accounts in Chrome.
The issue persisted even when switching between Admin and other roles with less permissions - no scripts would be loaded among 5 client scripts deployed on that record type. Workflows kept running normally.
The issue resolved itself about 10-15 minutes later without changing anything.
If you have not done anything and it worked, this looks like caching problem specially if it is the first time you've access NetSuite and that account using Firefox. I've come across situations before where I needed to log in, log out, clear browser cache, reload, restart laptop (occasionally only if all else fails). Maybe the next time it happens, you wanna try to close your browser, refresh and clear its cache (hard clear). I hope it helps.
WELCOME TO THE ORACLE NETSUITE COMMUNITY! WE HIGHLY ENCOURAGE YOU TO PERSONALIZE YOUR COMMUNITY DISPLAY NAME TO MAKE YOUR ACTIVITY MORE MEMORABLE. PLEASE VISIT THIS FAQ FOR INSTRUCTIONS.