Uploaded several sketches with no problems. Then on the next attempt get the common messages about com port. The problem is, Arduino 022 says it doesn't recognize com3 which is the one I had been using successfully. Device manager still shows Arduino Uno as com3, but the IDE serial port list only shows com5 and com6. I've had this happen several times before. If I then go into device manager and change the Arduino port to say com5, the IDE will show only com6 in it's list. Like a dog chasing it's tail. I'm running Win7 x64.
hi denniscj7, sorry to go inside of your post, im actually fighting with similar bug, definitively this sounds the origin of all on windows troubles with UNO ( and surely for some Duemillanove).
maybe thefollowing might help any developper of arduino IDE: COM port used not showing up, or replaced COM done in windows makes things no more working
In external apps, the UNO is well opened in the good com port. but no communication from another app is possible.
Some questions about IDE: does it refresh really on windows COM PORT table ? from where does it get its listing of used COM PORT ?