If the crown is still firm and healthy (and it looks like it is) the most likely cause is hot air - they dislike temperatures over 60F. Other possible cause is direct sunlight or underwatering, but I'd go with the heat problem - have you had your heating on?

Hi Bamboo iv had Central Heating On but this is away from direct heat on a Shaded Window Sill ? It was a very Dry Plant when i purchsed it few wks ago but since iv had it its been kept moist!

If you've had your heating on and this has happened since then, it'll be the heat - none of us will tolerate sitting in a room that's only 60 degrees F, we'd be cold, more usually temperature's set around 70. Is there a cooler windowsill you can use, direct sun regardless? I've found they don't mind winter sun, well, that's my personal experience, so if I have them, I keep them on a windowsill away from a radiator with the window open above. And I draw the curtains at night and leave the plant between the curtains and the glass - that's a cold place to be, but they don't mind at all (as long as the window's not open all night, that is)

Maybe its been kept to moist! Happens to them at the nursery where I work. And when you water, water from the base.
The crown tends to be burried deeper than the soil level, so perhaps carefully remove some of the soil from the top of the pot and slightly away from the corm.

It could be a hang over from the way it was looked after before you bought it. You don't know how long it had been a "very dry" plant in the shop and it may have been stressed. With luck, it will do OK next year.

Thanx every 1 for all the Comments i know more now about how 2 care for it :)

I find they lose the odd leaf this way as the season progresses it is a steady subtle loss of colour. as Bulba says thisloss of a few leaves together is probably due to what happened to it before you rescued it. Give the plant a feed with something like babybio to help encourage newer growth. also keep an eye out for 1-2mm long slim black thrips. they are a problem pest and cause distorted leaves and buds.

I have mine on windowsills that dont get blocked by curtains so the temperature cools as the house cools at night but they dont get a quick drop in temp that often accompanies closing the curtains.

My two cyclamens were flowering away happily but the leaves were all turning yellow and falling off. I picked one up to investigate more closely and the corm came straight up out of the soil. Neither corm had a single root in sight and closer investigation revealed the dreaded vine weevil grub had done its dastardly work, and there were one or two in the soil including one actually in the corm itself.

I repotted but have little hope that they will survive although the flowering is still continuing. Any idea of their chances?

I have actually left the pots outside but I assume they will not stand the winter temps in the Czech Republic which regularly go down to minus 20C.

Cestina, I think that there is every chance the corms will survive. I aquired a rather special cyclamen as a seedling a few years ago which grew well and I was going to take it to our October show this year. In September the buds and leaves fell off and investigation found - vine weavil grubs, grrr. I cleaned up the bulb and replanted it in new compost and two weeks ago noted new leaves coming through. If I can keep the corm healthy it will produce new roots and be back to normal next autumn.
Minus 20C in pots is rather extreme for any bulbs. Do you have a porch or something that does not get so cold to overwinter them in?

Thanks Bulbaholic - in that case I will ask my friend to pop them into the house where the temps are held at 11C during the winter, lowest I can turn my heating to........

Thats good, Cestina, cool but not freezing. They need some TLC at the moment.