Control Panel, Mouse, check all the settings and change if necessary. Try a different cursor. Make sure the correct model mouse is selected and the right software is installed. You should say what model mouse and which type--wired, wireless, bluetooth, etc. Also make sure no Accessibility Options (XP) are selected in Control Panel, Ease of Access (Vista.)

i hv tried that already

 

and my PC specs are

 

Intel(R) Core(TM)2 Quad Processor Q6600
16X DVD+/-RW with Dual Layer Write Capabilities
500GB SATA 3.0Gb/s Hard Drive with Native Command Queuing
Genuine Windows Vista(R) Business 32 bit (English) DVD Media Included
256MB PCIe(TM) x16 ATI Radeon(TM) HD 2600 XT w/TV-Out, HDMI Out & Dual DVI
McAfee(R) Security Center(TM) - 15 Months OEM (English)
3GB (2x1GB/2x512MB) NECC Dual Channel DDR2 667MHz SDRAM Memory
22 ViewSonic VX2235wm 22 Wide Screen Flat Panel

Dell(TM) Optical USB Mouse

Dell(TM) USB Quietkey(R) Keyboard(English)

I found the same problem on every Dell system (Vostro, Inspiron) using ATI 2600 video card.

It is a problem related only to the video driver.

 

--> The location of mouse cursor as displayed by the card is not the same that Windows is considering to use.  You ckick somewhere, but windows is convinced you are clicking a centimetre right-and half-centimetre under that position.

 

Downloading the most recent from ATi site does not solve.

Dell driver download for Vostro 400 does not show ATI 2600 card as a driver download choice and ATI 2400's is not the right driver.

 

SOLUTION:

You need to search Dell site for downloads related to Inspiron 530 

The driver I user to solve on a serie of Vostro units and some Inspiron starting december 2007 was 

R170619 - AMD Radeon HD 2600 XT(256MB PCI-Express x16 (Dual DVI) RV630)

http://ftp.us.dell.com/video/R170619.EXE

Dowloading and installing this video driver from Dell site perfectly solve.