Inconsistent Errors

[eluser]wowdezign[/eluser]
Hello all. I have a CI form that I am having trouble with. This form when submitted by an authenticated user enters data into a database.

Problem:
The form fails at times. HOWEVER, the error only occurs on the same machines. I have three computers That I test with, Vista, Vista, and XP.

My customer has a Vista machine also. When he submits the form from his machine, the form errors out around 80% of the time, no matter which browser we try IE7 or FF. His colleagues are also having the same issue with their machines. However, not once have I had the error happen when I submit the form from any of my test machines. The puzzle is trying to figure why this form doesn't consistently fail or work while using his machine or the other machines.

I took my laptop to his office and plugged into his internet connection, and posted the form with no problem, switched back to his computer and it failed a few times, then started working. Once the form starts working, it works consistently, then the next time he logs in and tries to post, the form fails again.

Any thoughts on what this could be?

[eluser]Aken[/eluser]
You'll need to share some of your code, and the specific errors that are being received in order to help diagnose.

[eluser]JoostV[/eluser]
If you use session in your form (e.g. cptcha or csrf token) this could be session error. Sessions tend to get messed up if the clock is not set to the right time.
Have you checked if the system clocks on your server and client's Vista machine?

[eluser]wowdezign[/eluser]
Thank you JoostV. It sounds like you were able to hit the nail on the head. I am using a form token. No I haven't checked but these users will be from different time zones.

Any specific suggestions on how I can move forward? This application will have users logging in from all over North America.

[eluser]JoostV[/eluser]
Setting your server clock to the right time should do the trick. I have no experience with users loggin in from different timezones, but it should't be a problem.