Serial.print WHY WON'T IT WORK

That makes sense! In a Windoze sort of way.

Now change the title of your first posting to Serial.print [Solved]

PeterRabbit: PROBLEM SOLVED I deleted Arduino software from both computers and reinstalled. Now serial.print works perfectly. Thanks for all your thoughtful suggestions.

Did you check the version of the software you deleted before you did it? The software needs no installation so I'm curious what caused the problem and why it is solved.

I use Windows 7 and don't have any issues with the arduino IDE (but then I'm able to correctly spell Windows). 8)

liudr: Did you check the version of the software you deleted before you did it? The software needs no installation so I'm curious what caused the problem and why it is solved.

And he did say that it was not working on two computers, so an intermittently dodgy install would be an odd ting to happen on both.

Good observation. I think what happened was on both computers the wrong drivers were automatically installed. Both computers are windows 7. Both showed the same symptoms.

I subsequently deleted and reinstalled Arduino UNO software on both computers. One computer automatically found and installed the correct driver. It now works with no problem at all.

The other computer has automatically installed a wrong driver which communicates nothing. It's worse than the previous driver which would at least download sketches. Initially I was not aware of the mishap.

Now I can't get this second computer to accept the correct driver. I believe the correct driver is "arduino.inf". It repeatably gives me the message "Windows has already installed the correct driver". Your suggestions are more than welcome. Thanks.

Right click computer, choose manage. Then on left side click device management. On right pane, find ports and find the serial poer, you have to have the arduino connected. Then right click the port and choose uninstall. Then unplug and plug again. You should get message about install driver, choose arduino folder and arduino.inf

If you have two computers convert one of them to Linux - no additional drivers to install!

...R

liudr: Right click computer, choose manage. Then on left side click device management. On right pane, find ports and find the serial poer, you have to have the arduino connected. Then right click the port and choose uninstall. Then unplug and plug again. You should get message about install driver, choose arduino folder and arduino.inf

Problem with above instructions These instruction worked well until at the end. my computer once again automatically installed the wrong driver. It didn't give me the opportunity to browse for "Arduino.inf". What do you suggest. Thanks so very much.

Have you tried using device manager, right clicking on the com port in question, chose properties, then use the update/uninstall/install driver options? I have two com ports showing, one is the arduino uno, and the other is a standard comport for my arduino with the FTDI serial chip.

Thanks for your suggestions. I have been able to apply them, but my computer still will not accept the new driver. Any other ideas? Thanks.

Problem solved. I deactivated the virus protection and reinstalled.

I see. I'll keep that in mind. I'm getting new computers.

Oh, BTW, Arduino IS a virus though. Once you catch it, you'll be carrying it and infecting others with it. So the anti-virus software has its rights to block it :D