It's a common mistake to abuse
. It's good for a simple static presentation of a constant picture (or changing sometimes), nothing else. When you try to use it for anything dynamic, interactive or animated, it becomes not help but a hassle for implementation and a useless resource-eater, compared to a custom control derived from
Here, I explain what to do instead: How do I clear a panel from old drawing
However, if you need a one-time rendering of your ellipses, do what John advised to do, it will work fine.
Oh, sorry, I did not see: a timer event. No, not, certainly no
And avoid using timer; using a separate thread is much better: more reliable, easier to implement and maintain.
Please see my collection of the references to my past solutions of threading:
How to get a keydown event to operate on a different thread in vb.net
Control events not firing after enable disable + multithreading