iSoft's shares have slumped over 75% since January

The main reason profits will miss forecasts is because iSoft plans to change the way it reports earnings.

ISoft said it now expects pre-tax profits of between �3m and �7m for its past financial year compared with an earlier estimate of �17m to �22m.

The company's shares already have been under pressure, but they dropped 32 pence, or 39%, to 51p on Thursday.

'Area of uncertainty'

They were hit hard in March, when they have lost three-quarters of their value, after it emerged that the company was blamed for delays in a �2bn plan to upgrade NHS computers.

There has been speculation that the project may be delayed for as long as two years, a situation that may affect the company's cash flow, analysts said.

"This remains the greatest area of uncertainty," brokerage Bridgewell explained. "While we would not expect iSoft to be kicked off the programme or fined, this is of course a possibility and will remain a concern."

Morgan Stanley, iSoft's broker, said that it had suspended its recommendation on the company's shares because it lacked "visibility".

In an effort to reassure investors, iSoft said it was looking at ways of cutting its costs, including reducing its staffing levels and selling off assets.