arduino uno program upload exception (ser_open() & stk500_getsync())

I cannot upload program to arduino after the last upload time, but Serial Monitor is displaying previous program result.
There have two different error message between arduino-1.0.5-r2 and arduino-1.5.6-r2 (arduino IDE).
p.s. i do not install ftdi usb driver.
What can i do now?
Also, i want to ask this "avrdude stk500_getsync() not in sync resp=0x30" is arduino problem or PC problem?

Driver Manager

https://drive.google.com/file/d/0B-9jhrQur3BpSW9Uamo0dnY3VTg/edit?usp=sharing
<<arduino-1.0.5-r2>>
avrdude stk500_getsync() not in sync resp=0x30

https://drive.google.com/file/d/0B-9jhrQur3BpaXpqY1FFWFFCMXc/edit?usp=sharing

<<arduino-1.5.6-r2>>

Sketch uses 2,550 bytes (7%) of program storage space. Maximum is 32,256 bytes.
Global variables use 184 bytes (8%) of dynamic memory, leaving 1,864 bytes for local variables. Maximum is 2,048 bytes.
avrdude: ser_open(): can't open device "\\.\COM4": The system cannot find the file specified.


processing.app.debug.RunnerException
	at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:125)
	at processing.app.Sketch.upload(Sketch.java:1719)
	at processing.app.Sketch.exportApplet(Sketch.java:1625)
	at processing.app.Sketch.exportApplet(Sketch.java:1597)
	at processing.app.Editor$DefaultExportHandler.run(Editor.java:2397)
	at java.lang.Thread.run(Unknown Source)
Caused by: processing.app.debug.RunnerException: Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
	at cc.arduino.packages.Uploader.executeUploadCommand(Uploader.java:111)
	at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:123)
	... 5 more


https://drive.google.com/file/d/0B-9jhrQur3BpRWE3aXhWX3JJUlE/edit?usp=sharing

hey did you manage to solve this problem? i have the same problem but did not manage to fix it

try to use another arduino

yes i had a second one and it worked .... does that mean that the first one does not work any more?