All of a sudden, all of our websites (on different web servers) with Form Master are showing "Insufficient system storage. The server response was 4.3.1 out of memory" when users try to submit a form. There is plenty of disk space on the web and database servers, and there is a lot of free RAM available. Any ideas?

How many rows and columns do you have?

2 Cols
6 Rows

The data is being saved to the database

We have had out of memory errors before once but the user had a form with 20 coluns aned 125 rows. There is no way that is the issue with 2 x 6 Ar you uploading a file?

Nope, just small forms. No file uploads. Sometimes it shows "The operation has timed out." in DNN as well.

I would start with your host. Something is not configured correctly on the server. If this is a virtual host they may have your memory quota set too low for DNN.

We are our own host - any suggestions for what settings I should look for? It's not a virtual host, but a real site in IIS.

Could you supply your Operating system Win 2003/2008

One server is 2003, the other is 2008. (1 website on each different server)

Threre are many reasons why the sever may runout of memory. I am not an IT professional. Check your processes which are running your web applications in Task Manager. In 2003 you would look for w3wp.exe running under the NETWORK SERVICE account and ckeck the memory usage. Check the application pool an see what the value of the Maximum CPU usage is.