There's a lot of talk about spyware and malware these days. But how do you know if you're infected with it?

Will your PC stop working as expected? Will your financial data be lifted without your knowledge? And if you discover that your computer is infected, what can you do about it? Read on for some answers.

Q: In recent weeks Internet Explorer 6 has been crashing periodically, giving me the message "IExplorer.exe has generated an error." I've determined that the crashes happen when I'm working in forms online, typing messages in forums or filling out requested information. I've installed or changed nothing on my computer.

A: Crashes such as this can be caused by spyware or malware. But more specifically, they're often caused by ActiveX controls or add-ons to browsers that may have been installed with of without your knowledge. Spyware and malware can fit into this category.

First, download, install, and run a free spyware removal tool such as Ad-Aware (http://www.lavasoftusa.com). There's no point in taking further steps until you know you've taken some effort to rid your PC of malware, which can cause such issues.

If this doesn't solve the problem, pare back any changes you've made - or allowed to be made - to Internet Explorer or another browser on your system. Such changes would include the installation of toolbars, integrated stock tickers or weather modules, search features tied to the browser, and so on.

Finally, make sure that your browser has been updated with the latest patches and security fixes. Sometimes as a last resort, a complete reinstallation of the browser itself can help. You can generally find the full installation files for any browser by visiting the browser maker's Web page.

Q: Every time I launch my browser, dozens of browser windows pop up, and then one appears that advertises a spyware removal tool. When these windows open, my system slows to a crawl, and the entire computer is rendered unusable unless I manage to close all the windows. I tried using several spyware removal tools, but nothing worked. Any ideas?

A: Your computer has been infected with what's known as a browser hijacker. The simplest of these hijackers changes the page that your browser displays upon startup. The motive is transparent: someone wants you to see the page to which you're being directed.

Simply going into the options menu of your browser and setting the page back can fix this type of browser hijacking. But the more pernicious browser hijackers change settings in your Windows registry, settings which enable the browser to spawn multiple instances of browser windows of all sizes - and it can all happen so quickly that your computer is effectively disabled.

Your best hope of removing such severe cases of browser hijacking is to download and use the following adware removal software: Spybot S&D (http://www.safer-networking.org), Ad-Aware (http://www.lavasoftusa.com), and SpySweeper (http://www.webroot.com). Each of these products has its strengths and weaknesses, and each may find spyware that the others miss.

If none of these programs works and you feel you're a fairly advanced computer user, try downloading Hijack This from (http://www.spywareinfo.com/~merijn/programs.php), but be sure to read the tutorial and the user forum before deleting anything with the program. Hijack This will list for you every search and start page setting on your system, and you can use the tool to delete any entry that you have not specified yourself.

As a last resort, you may need to reinstall your browser or use the windows system restore utility to roll your PC gets back to a previous, working state. System restore is located in the start menu under programmes, accessories and system tools. Once system restore is open, you can click "Restore my computer to an earlier time," and click Next to follow the instructions.

Q: I use my Windows computer for online banking and credit card management. I'm very concerned about the reports I read regarding financial and identity theft online. How can I be sure my computer is protected?

A: To be as sure as possible that any computer on which you have sensitive financial data has not and will not be compromised, you'll need to enlist the help of real-time anti-spyware software.

One of the important differences between the free anti-spyware packages such as Ad-Aware and those that cost money is the real-time monitoring that goes on constantly in the background. Free scanners are on-demand products, meaning that they run only when you ask them to. Lots of spyware can infect your computer when you're not thinking about it. So constant, behind-the-scenes monitoring makes sense. Ad-Aware Pro and Spy Sweeper are highly regarded products that offer real-time monitoring.

Also consider upgrading your operating system to Windows Vista if you haven't already. One of the primary advantages of Vista is its beefed-up security controls, which include an anti-phishing filter in Internet Explorer and safeguards that prevent software from installing on your computer without your approval.