If your computer is taking ages to boot up and is very slow while running programs, it might be due to a number of factors:

Problem 1: Not enough RAM
Problem 2: Temporary files have built up on your hard disk
Problem 3: Your computer has been infected
Problem 4. Not enough space on the hard disk
Problem 5: Your Direct Memory Access (DMA) is disabled

If this is a new change instead of a gradual one, the first question to ask is: "What has changed on the computer to cause this?" Have you installed any new hardware or software? If you have you can try removing the software or hardware and see if that fixes it. If it doesn't, some startup programs may be having trouble or utilizing too many system resources. If you are using Windows 98/ME/XP (2000 is excluded) you can go to your Start Menu, click on Run, and type in msconfig. Then go to the Startup tab and deselect items that may not be necessary to your computer. Don't panic! If you deselect the wrong item, you can always re-enable it.

If this has been more of an on-going change, you may have also accidentally installed software known as spyware or adware (definition). You can use a program like
Ad-Aware or SpyBot to remove this unwanted software from your PC.

If that doesn't correct the problem, you can run some basic maintenance routines on your PC such as a scandisk, defragment, and cleaning up temporary files.

Helpful Rescources:
Answersthatwork.com
This is a great resource if you want to know what a specific startup item does.

First, do not panic if your computer seems to have a virus. Common software problems, such as program execution errors and corrupted files, can create symptoms that appear to be virus-related; it is important to distinguish between virus symptoms and those that come from corrupted system files. Try to rule out more standard causes before suspecting a virus. For example, if you just installed new software, try uninstalling it and see if the problems disappear.

But if your computer begins to act strangely or is unable to do things it has always done in the past, it may be infected with a virus. Symptoms such as longer-than-normal program load times, unpredictable program behavior, inexplicable changes in file sizes, inability to boot, strange graphics appearing on your screen, or unusual sounds may indicate a virus on your system.

If you have difficulty finding a removal tool you can use Google and search for '<virus> removal tool', where <virus> is the name of the virus that has been identified. I highly recommend having a virus scanner installed. Avast makes a fully certified, free to use, virus scanner the Avast Home addition. If you are looking for a commercial solution, the website has a pro version you can perchase. Alternatively, your internet service provider may offer a free security package.

On the other hand, if you do have a virus scanner installed, it may be a matter of making sure that you have updated it with the latest virus definitions and scanned your computer. The specifics on how to do this vary with each product, consult with the manual or help menu.

Helpful Resources:
computer cirus Remove
Remove Spyware and Viruses

A computer usually makes a weird “whistling” sound if it has detected a problem over the temperature of your processor. This can come from an overheating issue caused by the absence or defect in the CPU/ power supply fans. If the fans cannot provide sufficient ventilation to your computer’s components, this will cause your hardware to overheat and damage the components inside the CPU. More than often, your computer will shut down just after this “whistling” noise to prevent jeopardizing your computer system.

Sometimes, cables from inside your CPU might also be blocking the fan from working properly. They can get stuck in between the fans and be the source of this weird noise.

To solve this issue, follow the steps below:

Step 1:
Shut down your computer immediately (if it has not already shut down automatically).

Step 2:
Unplug the power supply cable from the CPU and make sure that you have unplugged any devices before unscrewing the CPU cover.

Step 3:
Make sure that no cables are obstructing the fans and that the right cables are plugged in the fans.

Step 4:
Remove any dust particles that might have accumulated inside the CPU with a compressed air sprayer designed for this task. If you do not have one, you can make use of a soft paint brush.

Step 5:
Without closing the CPU, be very careful while connecting the power cable again. Switch the CPU on to check whether the fans are working properly.

Step 6:
If this doesn't solve your problem, you may need to buy new fans to have a proper ventilation for your CPU... or you can get SB to help you with this issue.

Excessive pop-ups are typically come from two sources:

Spyware, and Added by the website designer (to generate revenue).

For basic pop-up blocking, you can use Google's pop-up blocker tool. It appears as an extra toolbar in your Internet Explorer browser. This will block most legitimate pop-ups, but won't help much against the adware infections mentioned above. Read about it and download it at: http://toolbar.google.com

It's frustrating to not have control over advertising. Unfortunately, the Internet functions in a way that sometimes feels like you don't have control over your own computer! Take control and don't let your PC get pushed around by advertisers.