BUILD FAILED Unable to delete file hsqldb.out

Process Explorer shows you information about which handles and DLLs processes have opened or loaded.

• Download Process Explorer from Microsoft site and run the program.
• Click the Find menu, and choose Find Handle or DLL...
• Type the file name (name of the file which is locked by some process.)
• After typing the search phrase, click the Search button

You should see the list of applications which are accessing the file.

Few words about windows service

What is windows service?
it's a program that runs invisibly in the background. But can't the same thing be said for a number of programs that run in the background such as anti-virus programs. Yes, but the real difference is that services load and start running whether or not anyone logs into the computer, unlike a program that is launched from the Startup Folder under All Programs. 

Two ways to view Services
1) Typing msconfig.exe in the Run box accessed via the Start Menu, followed by clicking the Services tab. If you want a quick visual of which items are running or stopped, this is fine, but the information is limited. 
2) launch services.msc from the Run option on the Start Menu.


How To Delete A Service? 

• Start | Run and type cmd in the Open: line. Click OK.
• Type: sc delete service-name
• Reboot the system

 How To Create A Service?

• Start | Run and type cmd in the Open: line. Click OK.
• Type: sc create service-name
• Reboot the system

Not able to open C drive on double click

Are you not able to open C drive or any other drive when you double click on Hard disk drives? This is caused due to Virus attack. And possible other problem related to this is unable to display hidden files.
Anyways nothing to worry. This can be corrected, follow these steps
1) Open command prompt i.e start -> run -> and type "cmd"
2) cd\
3) attrib -r -h -s autorun.inf
4) del autorun.inf
5) Repeat this for other drives like d:, e: etc

Reboot your system, your problem will be solved.