Error connecting to the target - in TMS320F28335

Hi..

I'm getting the following error in Code Composer Studio 4 while programming TMS320F28335.

Error connecting to the target:
Error 0x80000240/-151
Fatal Error during: Initialization, OCS,

then if i retry:

Error connecting to the target:
Error 0x80000200/-1047
Fatal Error during: OCS,
PTI_ERR_EMU_CLOSE Error Occured at 0x00000000

I re-installed CCS4,but the problem persists.

CCS4 was working perfectly before.But now, even for basic codes this error is showing.

Please help me to rectify this error.