With a minor addition, you can prevent your plastic drawers from derailing.
I recently bought a 10 drawer cabinet to organize some of my "raw materials".
Help I'm a Hoarder comes to mind.

I like the cabinet and do recommend it. I picked my up for about $35. If you want to locate it online, you will likely get a hit by googling: Storage Cart - 10 Drawer

As seen in the photos, it is essentially a stack of plastic trays each of which slides into "C" tracks on the left/right sides. Unfortunately, when the tray gets a bit heavy, it does flex a bit which contorts the geometry of the top of the tray.
The trays tend to pull inward and thus can come "off track" when sliding on the rails.

To fix the problem, I installed a reinforcement which spans the top of each tray.
I used some scrap wood found in the garage. To make the result more clean, I used rivets instead of screws.

Step 1: What You Need

You will need just a few items for this instructable:

Materials
Rivets
Small Pieces of Wood
and of course you'll need a set of drawers!

Tools
Rivet Tool
Ruler
Pencil
Drill
Drill Bit
Screwdriver

Step 2: Droopy Drawers

Here's the problem. The drawers are not strong enough to hold their shape after a certain amount of weight is placed in them.

Step 3: Fix the Problem

We'll fix the problem by reinforcing the drawers with some small pieces of wood. My wood was about 1.50 inches wide and .375 inches thick. What you get looks sort of like wooden window blinds. In fact, I think that's what mine are. I just found it in the garage... It will be important to cut the boards to the correct length. I did this by measuring the width of the inside upper edge of the drawer. I think mine was about 10.625 inches.

You'll need one board for every shelf that you want reinforced. I did all ten.

Step 4: Drill Holes for the Rivets

You will need to drill holes in the sides of the shelves and in the ends of the wood pieces. I drilled two holes in each drawer. The holes are near the upper lip on the left and right sides of each drawer. They also are place halfway between the front and back sides.

Also you will need to drill holes in the ends of the wood pieces. This is CRITICAL. If you do not drill a wide enough hole, you will likely split the woodl. I drilled all my holes (shelves and wood) at .125 inches (that's 1/8 inch). I chose that size because that is the size of the rivets I used.

Step 5: Fasten the Wood to the Drawers

I used rivets to fasten the wood to the drawers. I used rivets instead of screws because rivets have a lower profile. You cannot countersink the plastic drawers very effectively. You might be able to use screws but I avoided it.