Can't connect to the net!

Hello.I cannot connect to the internet under ubuntu;under windows xp I can.and I could connect under ubuntu before

Please tell me what's getting wrong here?

I am connecting to the internet through a wireless network.

I suspect having a malware.What about you

More info needed ;) What wifi chip are you using, has it worked before?

And it's almost certainly not malware, there's close to none for Linux :)

D-Link wireless Network adapter..........(not sure about the actual name but it is D-link wireless NIC)

USB or PCI? If it's USB, post the output of lsusb, if it's PCI, post the output of lspci.

It's PCI

here is lspci output:

00:00.0 Host bridge: Intel Corporation 82G33/G31/P35/P31 Express DRAM Controller (rev 02)

00:01.0 PCI bridge: Intel Corporation 82G33/G31/P35/P31 Express PCI Express Root Port (rev 02) 00:1a.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 02) 00:1a.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 02) 00:1a.2 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 02) 00:1a.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 02) 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 02) 00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 02) 00:1c.3 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 4 (rev 02) 00:1c.4 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 5 (rev 02) 00:1d.0 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 02) 00:1d.1 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 02) 00:1d.2 USB Controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 02) 00:1d.7 USB Controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 02) 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 92) 00:1f.0 ISA bridge: Intel Corporation 82801IB (ICH9) LPC Interface Controller (rev 02) 00:1f.2 IDE interface: Intel Corporation 82801IB (ICH9) 2 port SATA IDE Controller (rev 02) 00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 02) 00:1f.5 IDE interface: Intel Corporation 82801I (ICH9 Family) 2 port SATA IDE Controller (rev 02) 01:00.0 VGA compatible controller: nVidia Corporation G86 [GeForce 8500 GT] (rev a1) 03:00.0 IDE interface: JMicron Technology Corp. JMB368 IDE controller 04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 01) 05:00.0 Network controller: RaLink RT2561/RT61 rev B 802.11g

Apparently it's supported. Have you tried moving it to a different PCI slot or reseated it?

I restarted my PC and now am able to connect via ubuntu.So do I need any anti-virus?

Nope, none at all, unless you want to share lots of files with a Windows installation/partition/friend with Windows, as you might accidentally transfer over a Windows virus.

I transfer files from windows computers on my USB flash memory

http://www.avast.com/linux-home-edition

Avast has a free linux version and there is ClamAV

I just tested it and it works using my windows registration You dont need it for linux. It could still be useful to scan windows files.