We observed EX Draconis in BV I colours for 40 nights, covering 3 outburst events, with the aim to study the disc evolution. Here, we present a preliminary eclipse-mapping study of some of the B band light curves obtained during the outburst in August 2000.

After the unexpected superoutburst of WZ Sge on July 23, 2001, the light curve was dominated by the orbital variability with a switch to dominating superhumps after August 5. The time series analysis of our data has shown, that the superhumps have started at the early stage of the superoutburst.

We report on time-series photometric observations in the earliest stages of superoutbursts of the extreme dwarf novae, AL Com and WZ Sge, which started on 2001 May after the 6 years quiescence and on 2001 July after the 23 years quiescence, respectively. We detected the growth of ``early superhumps'' during the each rising stage. Our observations reject the mass transfer instability for the trigger of the superoutburst of WZ Sge stars, and show the existence of some relations between the ``early superhumps'' and the spiral structure, which gives a hint of the origin of the ``early superhumps.''

We analyse the fine structure of the type IV radio burst, during the main phase of the 14th July 2000 major event recorded by the radiospectrograph ARTEMIS-IV, in the 110-650 MHz (10 Hz sampling rate) and the 270-450 MHz (100 Hz rate) range. In this report we focus on variations in frequency drift rate and repetition rate of fibers bursts. A pronounced asymmetry between the number of bursts with positive and negative frequency drift is noted at certain time periods. These variations follow closely the evolution of the magnetic structure associated with the major solar event and the onset of the corresponding CME.