Before I panic, can you advise?

[Paper Roses]

Yesterday I got a pop-up on my PC screen to this effect:

AVG notification. You are using too much memory. Close program and reopen.

Not too sure of the wording but I closed and reopened it. My computer is old and slow but I am not in a position to buy a new one.
Why this message all of a sudden. I have not added anything new. I know I have lots of programs on this machine that I never use. I wonder if I should call my computer Guru and have him delete some of the stuff.
I really don't know what I am doing so I need advice about what might be going on.

Are by "favorites" of which I have tons, taking up memory or is this infernal machine on its way out.

If I delete some of the programs I recognize, would this help?

Edited to add:

Just got a notice .. Mozilla Firefox crash report

[hlthe2b]

1. it just means you have gone a while since rebooting and all the programs

and web pages you've had open have used up RAM memory--which is different from storage memory. If you rebooted and kept a few less pages open at once, you were probably fine. That may have caused firefox to crash as well.

[JDDavis]

2. You need not delete programs from your computer

As the poster above this advised, you just had too many things open at once.

Newer programs and even some web pages use more of your RAM memory than they used to as they add more bells and whistles.

Not a reason to panic, but do discuss with your computer Guru if it is possible to add RAM memory to your current computer. Many older computers have only one or two gigabytes of Ram, and some of them can be "expanded" to 4 gigabytes, for well under $50, just by buying and installing a new computer RAM memory chip inside the computer. Some older models are not expandable, however.

[blackcrow]

3. If programmers today

had half the brain cells of older programmers, they'd write software that adjusted for available memory.

[Denzil_DC]

4. Some versions of Firefox can be buggy, and it can also be a runaway memory hog at times,

depending how you use it.

Also, get your guru to check what programs you have running on startup.

These are programs that load every time you boot up your computer, usually running in background so that you're unaware of them. Many of them can usually be disabled without worsening performance, but it's not a task for someone who's not confident.