strange problem - paint wont dry and running off the wall

hi, background to the problem is this:

bedroom walls originally painted in a darkish shade of normal silk emulsion.
decided to cover with base coat of white matt as new colour very light. discovered tin of matt was mouldy on top but having limited funds decided to "rescue" it and use anyway. apart from paint not feeling quite right on application and taking much longer than expected to dry off, it appeared to do its job.

However, one coat of new silk emulsion later I now have massive problems.

There are several areas on the walls where the new paint has not dried despite using a heater. About 95% of the 4 walls dried ok but the problem areas are a major worry and nothing I've ever seen or heard of before.
In a few areas, the paint is still wet or tacky while the surrounds have dried; and there is one quite large area where the paint has quite literally run off the wall and 24hrs later this run-off paint is still not dry on the rags used to mop it up. The run-off is very liquid.

There has obviously been a reaction between the matt basecoat and the new silk emulsion and, with hindsight, I now realise I should have just chucked out the mouldy matt -- BIG mistake, I'll never do that again.

I think I need to remove all wet paint somehow, sand off the matt then coat the problem areas with some kind of barrier before painting with my new emulsion.

Can someone please help me sort out this mess and get my new paint on the walls. I have a very sad granddaughter waiting for grandma to finish her room

thanks.

update on the cleaning - washed all tacky/drippy areas with warm soapy water using a soft cloth. This removed the new top silk emulsion and the crappy matt underneath; now waiting for washed areas to dry fully before sanding.

Help and comments as to whether I'm doing the right thing will be gratefully received. Thanks

You are on the right lines but you will need to spend some £ - look up "Zinsser" specialist paints on t'net. You will find something suitable for the size of the dodgy areas that will bind and seal them

Nige F, I will look into that immediately. thanks